/sci/ - Science & Math

How wise is it to double major in Computer Engineering and Applied Mathematics?

>>8150299
I am of the school of thought that double majoring is stupid in general. If you have the extra energy then use it for non-academic but constructive purposes, even if the double majoring only implies doing 1 or 2 more classes per semester.

But assuming that I am wrong then your combo is not good enough. You will likely get all the applied math you need from CE so if you really want to expand your knowledge you would be better off doing CE and pure mathematics.

Applied math degrees that I've seen are very low on math.

>>8150299
Double majoring is fucking stupid. You can probably pick up some classes in either field to fill up some general electives, but double majoring prevents you from getting in depth with anything at all.

Assuming anything is possible, is it possible for an impossibility to be impossible?

How is a gene drive selected for in a population? Especially one that can potentially kill the specie?

>>8150299
Just get your bachelor's in CompE or Applied Math then get your master's degree in the subject that you didn't get your undergrad in. I'd go CompE for undergrad that way you can make money and get your Master's degree in Applied Mathematics which you can make money and multiple fields.

>>8150318
that's an impossibly stupid question

>>8150318
If a set contains all sets, does it contain a set that isn't in it?

Is there a torrent for an electronic MCAT practice test? I hate practicing with pdf based ones because checking the answers is too damn slow.

>>8150304
What is degree in "applied mathematics"? Isn't a physics degree a degree in applied math?

>>8150354
If you assume that there exists a set that contains all sets then you are tacitly assuming that there is no set that isn't cointained in that set.

You are basically asking that if 1+1=2 then can 1+1=3??????? xD hurrrrr

Is computer (hardware) engineering the best for delving into building circuits and everything that follows?
Considering electrical engineering, just not sure on the differences in course material.

Just want to be able to build my own rudimentary circuits and random machinery in my free time.

Best path to get into scientific computing / applied mathematics?

Former biochemistry major, did two years then dropped out because of personal reasons, now want to go back to school. During that time studied math and got into it.

Don't really sure what degree to go back for. CS / Math, Comp. Engineering, Applied Math.

>>8150292

What should I specialise in?

>>8150322

Could you rephrase the question?

>>8150322
If you introduce a gene drive to 100 individuals among a population of 10000 then how does it become ubiquitous among the population? Why isnt it bred out?

>>8150414
Meant to reply to
>>8150409

>>8150322
>>8150414


Ok, well if it conveys a benefit to the inclusive fitness of the organism, then it is highly likely to proliferate throughout the population, obviously.

However, you seem to be specifically inquiring as to how deleterious genes manage to spread through a population and become universal.

So, it is possible that a gene is antagonistically pleiotropic, in that it conveys some form of benefit to survival or reproductive success in younger – fertile – organisms, however causes harmful effects in later life.

Now, to address your main concern, entirely deleterious genes that convey no benefit may proliferate through the gene pool providing that they do not reduce reproductive success by more than 30%.

Essentially, the competitive edge that a higher than 50% chance of transmission provides deleterious genes, is only stable when the detriment to reproductive success is less than 30%.

>>8150447
Can a deleterious gene strongly linked to a beneficial one can remain and proliferate passively with the other ?

>>8150462

Yes, of course, it's rarely the case that gene X is solely responsible for a particular phenotypic effect.

Any given phenotypic effect is generally produced by more than one gene, and its manifestation is dependent on the environment in which it is situated.

Therefore, a potentially deleterious gene that contributes to the inclusive fitness of the organism in the presence of another beneficial gene may proliferate through the population, again providing that the harm to reproductive success is less than 30%.

What's a good minor to take with a physics major? I'm leaning towards Comp.Sci., but Math or extended Physics seem reasonable too.

I plan on continuing to Astrophysics afterwards.

>>8150567

Minors don't mean anything. Just take some graduate level classes.

I remember at my school a math minor with a physics degree was literally just taking Linear Algebra as an elective and boom math minor.

But ya, doesn't really mean much in the long run.

>>8150577

Not him, but does one have to do anything to take graduate level courses or just pass undergrad courses and take graduate courses as an elective?

>>8150292
For associativity of composition of functions what is the order you evaluate the functions in the below composition?

(f o g) o h

do you evaluate h first then (fog) due to left to right evaulation or do you evaluate (fog) then h?


say

h(x)=y
g(y)=x
f(z)=t


It isn't cleat to me if you evaulate h first or (fog) due to the parathensis.

im trying to learn linear algebra but i dont understand how Ab1 becomes [11, -1], same with Ab2 and Ab3
(also how do i latex on here)

>>8150655
Just matrix multiplication

>>8150662
o shit im retarded, thanks anon

Will I be able to grasp stochastic calculus if the most advanced Calc course I've ever taken is AP Calculus BC?

>>8150405
niggers

>>8150791

Oh ok, sweet.

>>8150787
possibly. Depends how deep into the theory they get.
You need a primer on statistics too

What are the pros/cons of Civil Engineering?

>Inb4 it's not mechanical

>>8150594

Depends. You might have to contact the professor and ask for prerequisites.

Some classes legit require none.

>>8150611
Can someone address this question?

I believe you evaluate h then (fog)

Why are cosets defined the way they are? Or rather, why is the equivalence relation that generates them defined the way it is? My book defines them as:

Let H be a subgroup of G. Define x~y <--> xy^-1 is in H, x and y in G.

The equivalence classes are then Hg = {x in G : x=hg, h in H}

For some reason this just isn't clicking for me. Am I missing something?

>>8150611
Composition is defined by
(p o q) x = p (q x)
So
((f o g) o h) x = (f o g) (h x) = f (g (h x))
(f o (g o h)) x = f ((g o h) x) = f (g (h x))

Why do discretized values so often involve fractions, specifically 1/2? Most obvious example is spin half-integers. For quark charges in thirds I can presume history of charge reason enough, but spin seems to have involved half-integers from the beginning.

>>8151119
cosets are a useful notion, mostly because you define them to eventually define the notion of a normal subgroup, where the cosets themselves form a group

though the better definition of a normal subgroup is one that can be a kernel, these two definition turn out to be equivalent though

way down the line if you study representation theory or some higher algebra you might see double cosets in something called a 'Hecke algebra'

>majored in Math with a minor in Comp Sci
>feel like I barely learned anything

Is this normal?

if everything keeps going the way it currently has, and assuming we get fusion power implemented in 30 or so years, how long does /sci/ think we have before we get immigration crisis' and society breaks down due to global warming?

>>8151364
YES. It just means you have some self awareness. The only way to temper this feeling is to constantly learn.

>>8151315
Spin half-integers is due to the fact that this is the `natural' way to label eigenvalues of the Casimir of su(2). If you want, you could rescale these eigenvalues to find different integers, but then the rest of the physics community would look at you funny. So basically, it is no different than the quark charge thing; one starts with one convention and in order to stick with it, ends up with fractions elsewhere.

>>8150354
Yes.


No wait- No.

>>8151252
This is what I was looking for.

((f o g) o h) x = (f o g) (h x) = f (g (h x))

So, no matter if you do

(f o g) o h or f o (g o h), you will always evaluate it the same by doing h first, followed by g followed by f.

Correct?

so f o g o h could be evaluated without the parenthesis

say you want a job at novartis, should you go the molecular biology path or the biochemistry one?

>>8151569
correct

I really need help with this 'obvious' thing. I cant find this domain. Can someone help me and tell me HOW is this domain found?

Also, is there a general case formula for figuring out logarithms? Like, not by going to the power of 1, than if not to the power of two, than if not to the power of 3 etc till I get there, but a general case method to figure out to what power the base is, if it is equal to a 6 digits number for example.

>>8151680
log is only defined for numbers greater than zero. 2 is obviously greater than zero. When is (1-y) greater than zero? Whenever y < 1

I'm not sure what you mean in the second half. You want to, say, compute the value of log base 7 of 400 or something?
You can do it via Taylor series if you need a precise answer but the fastest way is to just try and estimate it in your head

>>8151680
you're finding the inverse of y, and so you now have x as a function of y (x=-log(1-y)/log2).

so the domain is all possible values of y you can put into the function -log(1-y)/log2

the only place y shows up is in the log(1-y) and this is defined for 1-y > 0 since log is defined only for positive numbers

and so 1> y

>>8151680
>obviously
lmao

the domain of log is (0,infinity)
when you have log(1-y), the domain becomes all of the places where 1-y is in (0,infinity)
in other words, where 1-y is greater than 0

>>8151710
>>8151711
>>8151712
thank you, it all makes sense when you say that logarithm must be greater than zero

Can also anyone help me with |x-1|<3 ?
Solutions are -2<x<4 but I just dont see what methods or things were used to come to that solution.

>>8151718
whenever you see |f(x)|<c for a function f and a positive real number c it means -c < f(x) < c

>>8151661
Thanks anon. This helped quite a bit.

>>8151721
I still dont understand

I understand that |x-1|<3 is the same as rood of (x-1) squared < 3 but I dont understand how exactly are solutions from -2 to 4

>>8151728
never mind, I think I got it, I think I misunderstood thing called subtraction of squares......

>>8151728
|x-1| < 3 if and only if -3 < x - 1 < 3 if and only if -2 < x < 4

What is the cardinality of the set containing all propositions undecidable in ZFC? By a proposition I mean a well founded statement in the language of ZFC and by undecidable I mean undecidable.
I don't have the best understanding of the concept, but I was thinking about it and was wondering if such a set was even well founded. Like could you possibly run into a situation where you'd have to introduce the concept of a class because the set of such propositions is 'too large', violating the axiom of regularity?

Are there any rules about functors between n-categories and m-categories where n doesn't equal m?
like, is it okay to say that there is a functor from Set to Cat?

>>8151743
thank you again, I wish I could thank you somehow in person, this example really helped me out

>>8151744
The set of propositions is countable what do you mean too large?
For the question I would guess the answer is also countable but I have no idea how to prove it.

>>8151744
>>8151764
Nvm. If the set of such propositions was finite you would get a complete recursively axiomatizable description of Peano arithmetic, contradicting Gödel's incompleteness.

What is the "geometrical" meaning or interpretation of the curl and divergence of a vector in R^3?

Like, what does it mean that the curl of E (electric field vector) is zero?

>>8151640
I checked out of biology quite a while ago, bit I do not advise a molecular biology degree. They are a dime a dozen these days, so you will probably be a more competitive applicant with a biochem degree

What would one study to prepare to get a physics degree?
Assume we're starting at middle school and working from scratch because I went to a hippie highschool where we were taught we didn't have to learn or produce to be special.

Taking my first, non-business calculus class this fall. I am average at math but want to be great at it. I went to a middle and high school in one of the worst school districts in the southern United States for math and I am fucked from that. I think my problem lies in the fact that I never really had a good education of algebra and because of that couldn't really build from there. Is Khan Academy the best place to learn that or is there a textbook that will allow me to learn more?

What does it mean when it asks "Find the smallest possible value x^2 + bx + c and of ax^2 + bx + c, for a>0" How would I find it, by what means?

I was writing a program and I found the need to take a number and break it up into its factors such that pq = c where c is constant, and |p - q| is as small as possible for any configuration of p and q where p and q are natural numbers. Using some algebra I found that some number k such that pk - q/k = 0 should be k = sqrt(q/p). From this I came up with an algorithm to take that square root, round it down to the nearest natural number, and then check for the nearest configuration of p and q. I expected there to be deviation above and below the rounded square root for the value of k, but it always seems that k is greater than the rounded square root. I'm wondering if this is true for any value of c, from my testing it seems to be as all numbers up to 2 million are with k being found above the rounded square root. Is there an obvious answer that I'm not seeing or is it more complicated that that?

>>8152155
Not only can you find super cheap (not necessarily that old) textbooks online, you can also access many of these books as free pdfs (just google free x-subject PDF).

Khan is great, especially for brushing up / relearning the basics but I've found Paul's online math notes to be indispensable when going through the calculus sequence. He even has comprehensive cheat sheets for algebra and trig so you can quickly see where you stand with requisite material before pursuing calculus as well as a reference for down the road.

Honestly if I were you i would make sure my understanding of algebra (especially Cartesian coordinate stuff) and trig is air tight before you take your calculus class. If you're wanting to do this quickly with a textbook, perhaps an anon can recommend a good pre-calculus book, or you can always search google.

>>8152202
thanks anon. I'm not really BAD at math at all. I am able to handle exponential and logarithmic stuff well but collapse with trig. I just really want to succeed in the class. I think without doing some prep I could finish with a mid B but I want to push that to an A and continue to succeed in upper level maths.

How do we eliminate vestigial structures from our genes?
shit seems like a waste of energy

>>8152178
Actually, it's always found below the rounded square root, my bad.

>>8152228
selective breeding or bringing back evolutionary pressure.

>>8152155
>>8152211
As the other anon said, the most important thing going into Calculus is to make sure you're very comfortable with all the algebra/trig that you did before it.

If you want to brush up on these concepts, Khan Academy is good, but I highly recommend also using a book. Reading through the material at your own pace and doing lots of exercises is the best way to learn math, Khan Academy is good if you need another perspective because you don't understand something.

One book which I've heard is good is Basic Mathematics by Serge Lang. I haven't read it myself, so I can vouch for it, but looking at the table of contents, it certainly seems to contain everything you would want to know going into a Calculus Course (except possibly chapter 17).

Immortality when?

i would like to study computer science, mathematics and physics and hopefully get phds in all 3. would it be best to triple major (i know i will get flak for asking that) or just go one by one. which should i study first

>>8152271
after you die.

>>8152282
You should study not falling for memes first.

When we go full retard and multiply by dx while solving a differential equation, the prof always goes "lol I hope there are no mathematicians watching", but doesn't explain why we can do that. I'd like to know what I have to study in order to understand when and why we can do that. Is it analysis? Calculus?

>>8152282
I'd go for math first so the others will be easier (for example, you will already know almost all the necessary math for physics and computer science after getting your math degree, you may even get credit for the courses you've already taken, like analysis or linear algebra, though I guess it depends on the country).

>>8151766
Thank you.

By 'too large' I mean you would violate the axiom of regularity.
'Too large' is a shitty description

I'm trying to learn organic chem from scratch.. the q was to draw the chemical and come up with a shorter name.
I don't have the solutions manual.. how did I do?

>>8151569
> so f o g o h could be evaluated without the parenthesis
Parentheses don't matter for associative operations. The definition of associativity is
(a @ b) @ c = a @ (b @ c)
With more than 3 operands, this rule can be applied repeatedly to move the parentheses around arbitrarily (generalized associative law). The order of the operands never changes.

>>8152169
> What does it mean when it asks "Find the smallest possible value x^2 + bx + c and of ax^2 + bx + c, for a>0" How would I find it, by what means?
Any equation of the form y=ax^2+bx+c is a parabola. The curve has the same shape as y=x^2, but may be scaled and translated. Roughly, a determines the scale, b the horizontal (x) translation, c the vertical (y) translation.

If a is positive, the parabola has a minimum in the middle (trough shape), going to +infinity as x goes to -infinity or +infinity.

The parabola y=(x+k)"2 is identical to y=x^2 except that it's shifted left by k. y=(x+k)^2 can be expanded to y=x^2+2kx+k^2. If you set k to b/2, then you get y=x^2+bx+b^2/4. This is the same as y=x^2+bx+c apart from a vertical translation of b^2/4-c. Significantly, both curves have their minima at the same value of x, i.e. at x=-b/2.

If you substitute x=-b/2 into y=x^2+bx+c, you get y=c-b^2/4, which is the minimum value the function can have.

For the case where y=ax^2+bx+c, factor out a to give y=a(x^2+bx/a+c/a) = a(x^2+b'x+c') where b'=b/a and c'=c/a. So the minimum is at x=-b'/2 = -b/2a, and the value is a*(c'-b'^2/4) = a*(c/a-b^2/4a^2) = c-b^2/4a.

>>8152343
A good rule of thumb in math is to do things only if you can prove you can do them.

>>8150292
I'm at my wit's end

Can you mount a keyed shaft (that will be rotating continuously) in a normal ball bearing?

Pls respond

>>8152575
The portion of the shaft resting on the bearing won't be keyed, of course (since it wouldn't fit, see: round peg in square hole)

>>8152343
Analysis

This gets stuck on "Running..." in Mathematica

x2 := x1 + Cos[a]
y2 := y1 + Sin[a]
Px := ((x1*x2 - y1*x2)*(x3 - x4) - (x1 - x2)*(x3*y4 - y3*x4))/((x1 -
x2)*(y3 - y4) - (y1 - y2)*(x3 - x4))
Py := ((x1*x2 - y1*x2)*(y3 - y4) - (y1 - y2)*(x3*y4 - y3*x4))/((x1 -
x2)*(y3 - y4) - (y1 - y2)*(x3 - x4))
Integrate[ArcTan[z / Sqrt[(Px - x1)^2 + (Py - y1)^2]], a]

Am I fucked? Does it look solvable at all?

>>8152635
All right. Do you happen to know what are the prerequisites to reading baby Rudin? Like knowledge of measure theory or set theory?

>>8152645
I've never actually studied it but I would imagine some basic set theory and some experience with proofs is a necessity.

>>8152362
thanks

>>8152314
i am not looking for money or a job. only looking for knowledge

>>8152645
Baby Rudin doesn't have any strictly formal prerequisites in the sense that it defines everything it needs from scratch.

However you should at least have a strong calculus course's experience (e.g. Apostol or Spivak).
Just use another book though Rudin is garbage as a learning tool

>>8152702
I've had calculus courses up to calc II. I have seen too much memery on the internet about rudin to know whether it's good or not, but hey, the book was free, and I saw some lectures recommended on stackoverflow to go with it.

>>8152716
You can still supplement with books that give in depth explanations. Try Abbot's Understanding Analysis (or some similar title).

I tried to get into Mathematical Analysis only to find out most of what I was reading didn't make much sense to me.

I am trying to build from the ground up a foundation that will help me understand all of this stuff so I decided to pick Spivak Calculus.

The first chapter talks about real numbers, mathematical induction, recursion, etc, and then a bunch of problems are presented.

I am ashamed to say that I am having a hard time to understand all of these concepts, ''proofs'' and mathematical language. And couldn't figure out how to solve any of the problems because my brain is just looking for a ''general'' method or a series of steps to solve them. Being completely honest, Ive never been taught this type of Math before.

So how do I make myself less dumb? When do these things ''click'' in ones brain?

>>8152786
Going from babby math to rigorous math is quite difficult, and can take a lot of time. It's something that is recognized to be traumatic.

>>8152823

I mean I took some calc courses back in college. That covered Derivatives, integrals, etc... But everything they teach me there was just so methodical. It was ''Use this equation to get the answer''.

This stuff is just so different from that.

>>8152786
I felt the same thing when I picked up spivak's calculus, I didn't see the motivation behind presenting those rules about numbers. I was like "yeah, I already know that 5+2=2+5, why are you telling me this?". I also felt that the things I had to prove were too basic and I wasn't sure whether I was "cheating" or not. Also, I just wanted to go to the more calculus-y chapters in general.
I haven't finished that book, but I have started uni since, and I think I can give you some help. I think you should write out which one of the 12 properties are you using at each step like this:

Problem 1/ii - prove that x^2-y^2=(x-y)(x+y)
Step 1: use P9 (if a, b and c are any numbers, then a*(b+c)=a*b+a*c). Let a=(x-y):
(x-y)(x+y)=a(x+y)=ax+ay=(x-y)x+(x-y)y
Step 2: use P9 again, twice:
(x-y)x+(x-y)y=xx-yx+xy-yy
Step 3: use P1 (associative law for addition) to add some parentheses:
xx-yx+xy-yy=xx+(-yx+xy)-yy
Step 4: use P5 (the associative law for multiplication) to turn xy into yx:
xx+(-yx+xy)-yy=xx+(-yx+yx)-yy
Step 5: use P3 (existence of additive inverse):
xx+(-yx+yx)-yy=xx+0-yy
Step 6: use P1 to add parentheses:
xx+0-yy=(xx+0)-yy
Step 7: use P2 (existence of an additive identity) to remove that fucking zero:
(xx+0)-yy=xx-yy=x^2-y^2 - changing xx to x^2 and yy to y^2 is just a question of notation, you don't need to invoke any laws to do that

Total noob question here. With the shell method, do I have to worry about inner and outer radii? I'm looking at a problem where a function is rotated around the y-axis, and there's a gap between the graph and the y-axis, so it seems like there should be an inner and outer radius, but apparently there isn't.

Do we have the technology to construct a machine that can pick up any light in the EM spectrum, and then stretch it all together into visable light on a display, so you could "see" in the entire spectrum?

>>8152971
yes

see infrared cameras, telescopes

>>8152991
I know we can do it with specific ranges, but would it from a pure engineering perspective be possible to capture entire spectrum, from more or less the same perspective and then make it into a visible light live feed on a screen?

so what is the purpose of a capacitor in a circuit?
i understand that they store electric charge but why is that useful?

>>8153004
Yes. Just capture something with different spectrum, then combine it. ez pz.

>>8153021
One of the main things they do is, along with a resistor, form a RC circuit which acts like a filter for certain frequencies.
Often you'll add a capacitor to the power supply of a chip to keep small disturbances from dropping the voltage below a threshold and turning off the circuit and making it behave weirdly.

>>8153021
A capacitor serve many functions. It's the only component that can discharge a lot of stored charge in a small timeframe, but it's mainly used to filter electricity so that you get a nice clean stream instead of unstable ups and downs in voltage.

>>8152534
Thanks man! This helps, I didn't really know what it was asking for, this is great.

>>8152178
I've read this many times and don't get it. Is c,p and q integers?

>I came up with an algorithm to take
>that square root,

square root of what? p/q? I thought you didn't know p or q... aren't they are what you want to find?

If I'm getting back into math after 3 years since pre-cal in high school what topics should i study first? (Matrices, imaginary numbers, logarithms, etc.)

>>8151383
About a week.

>>8153126
Sorry for being too vague, I'll try to explain better here.

There are two variables [math]p[/math] and [math]q[/math] whose product is some constant [math]c[/math]

[math]p[/math], [math]q[/math], and [math]c[/math] are all natural numbers which lets [math]p[/math] and [math]q[/math] can be thought of as a grouping of [math]c[/math]'s prime factors.

Essentially, I wanted to find values of [math]p[/math] and [math]q[/math] that satisfy the following three conditions:
- [math]pq = c[/math]
- [math]|p - q|[/math] is as small as possible
- [math]p[/math] and [math]q[/math] are whole numbers

Using algebra I found a general case for the number I would have to multiply [math]p[/math] by (think introduce a prime factor) and divide [math]q[/math] by (think remove a prime factor) in order to make the following equation

[math]|pk - q/k| = 0 [/math]

True for some value [math]k[/math], regardless of the values of [math]p[/math] and [math]q[/math]. By solving for [math]k[/math] you end up with

[math]k = \sqrt{\frac{q}{p}}[/math]

In order to find the nearest whole number value [math]k[/math] with [math]p = 1[/math] and [math]q = c[/math] that satisfy the aforementioned conditions, I calculated a number [math]l[/math] such that

[math]l = \lfloor k \rfloor[/math]

Then I figured that since I rounded [math]k[/math], I would need to search for values of [math]k[/math] both above and below the rounded value. So I used a for loop to search for values of [math]k[/math] above and below, find the first value of [math]k[/math] in each range that divides [math]c[/math] and then compare those values of [math]k[/math] to determine if

[math]|pk_1 - q/k_1| < |pk_2 - q/k_2|[/math] ([math]k_1[/math] being the value found below [math]l[/math] and [math]k_2[/math] being the value found above [math]l[/math])

The interesting thing was that the value of [math]k[/math] which produced the smallest difference was always [math]k_1[/math] which I questioned if it is always the case.

>>8152135
>biochem
I suspected as much, thanks anon

uhh, i have a stupid ass question

how come i can dissolve NaOH pellets and get a OH solution but I cant dissolve NaCl and get HCl solution from the water

>>8153463
Cl- is too weak of a base

I want to research for the sake of life extension, and as stupid as it sounds, I'm not sure how to actually begin with that (like what degrees and things I should probably have figured out already), is there even a point?

I just wanna live forever, man, I'm honestly fascinated, but that shit seems synonymous with anti-aging products and click bait nutrition ads.

Probably sound stupid for wanting to do it in the first place but y'know.

Also sorry for shitty wording, tired and can't into English right now

>>8153591
No, you will die, sorry.
You can always try the diet of some populations of some japanese islands, it was linked to high life expectancy.

>>8153595
Ah well, good enough, I'll look into that.

Do you think life extension will ever be a thing?

>>8153601
If you mean this by improving the quality of life, then it's alreadt a thing.
If you mean by acting directly on the body to counteract senescence, there is no reason not to.

>>8153604
The latter, thank you very much by the way.

>>8153591
>>8153601
some company is doing telomere restoration, it worked in animal studies and they've done it on an actual human (the CEO) and it lengthened her telomeres, they just need like $1 million of funding iirc to develop it further to reduce the cost of the treatment

the largest hyperreal... i think it's

ω^ω^ω^...^ω where ω is exponentiated ω times? but what if I add 1 to that? can you or is that the largest hyperreal? or is there no largest hyperreal?

>>8153713
>or is there no largest hyperreal?
i don't think so

>>8153713
You can add 1.
> is there no largest hyperreal?
Just add 1 until you find out.

>>8153730
Okay

I'm in driving school and the guy immediately to my left is a ginger who is furiously sucking his fingers and I think he already took 3 painkillers.

Is this kind of behavior caused by ginger inbreeding?

>>8153753
No, rather by ginger discrimination.

>>8153756
Well, I have never discriminated gingers. Until now.

ginger is an anagram of nigger

Just figured out an international consortium screwed a major thing up and has had consistently wrong data in their database for the past 15 months.

Dead chuffed tbqh, this made my month.

>>8153394
Thanks for the follow up. I think...

If pq=c, and p<q, then p<sqrt(c) and sqrt(c)<q. Further, since
(q-sqrt(c))^2 - (sqrt(c)-p)^2 =
(sqrt(q)-sqrt(p))^3 * (sqrt(p)+sqrt(q)) > 0, we see that p is closer to sqrt(c) than q is.
Since floor(sqrt(c))<=sqrt(c), p is closer to
this too.

Does that help?

Let [math] \sigma_n : ( \mathbb{Z} / 2009 \mathbb{Z} )^{*} \rightarrow ( \mathbb{Z} / 2009 \mathbb{Z} )^{*} [/math] be defined by [math] x \mapsto x^n [/math]. Determine the smallest [math] n > 1 [/math] such that [math] \sigma_n [/math] is a bijection.

What do?

I am actually having a lot of difficulty because I have no idea of what hes doing.

Considering the first function was f(x) = x^2

How did he go from that to the first one on this image?

>>8154484
[eqn]f(k)=k^2[/eqn]
[eqn]k=x+1[/eqn]
[eqn]f(x+1)=(x+1)^2=x^2+2x+1=f(x)+2x+1[/eqn]

>>8154490

Why is k = x + 1

where is this assumption coming from?

>>8154496
I thought that would make it clearer, it just means you replace the "x" with "x+1".
When [eqn]f(k)=k^2[/eqn] and[eqn] k=x+1[/eqn] then [eqn]f(k)=f(x+1)[/eqn], and [eqn]f(x+1)[/eqn] is what you were trying to find right?
So you just substitute all instances of [eqn]k[/eqn] in [eqn]f(k)[/eqn] with [eqn]x+1[/eqn] to get to the desired expression.

>>8154506
sorry, those equations were meant to be inline

>>8154506
>>8154510
wew lad

>>8154506
>>8154490

Thanks for the answer anon, I get it now.

>>8154163
The isomorphism class of the groups [math] (\mathhbb{Z}/n\mathbb{Z})^{*}[/math] is known (and that's all you need for the exercise).
(Look up chinese residue theorem and primitive roots, you'll need the prime factorization of 2009).

>>8154571
>[math] (\mathbb{Z}/n\mathbb{Z})^{*}[/math]
typo

I finished high school Friday
Im thinking about getting an actuarial science or statistics major
Any suggestions on how I can study this Summer

>>8154584

Enjoy a little bit of summer.

After that try to brush up anything you might be shaky on. I would suggest reading "How to Prove It" and work through the examples. It will help build your mathematical maturity.

If you want to learn a computer language, R is pretty useful for a statistics / Math major.

Book link: http://users.metu.edu.tr/serge/courses/111-2011/textbook-math111.pdf

>>8151764
>>8151766
Wait. How do we know it isn't uncountable?

>>8154614
They're finite strings in a countable language.

calc 3 fag here

a) represents the "height" of the total annual snowfall at the location (x,y)

i'm not sure what b represents

i do like these written, application questions but they never have the answers in the back for them. any help is appreciated

>>8154635
"height"?
More like total amount of snow. And the second would be the average (per unit of area).

>>8154639
that's what i thought for b

but for a i say height because its the total amount but only at one specific point. if i have a box of snow and im only looking at the dead center, the amount at the center could be described as a height, no?

I just met this asian kid.
He just read the definition once for whatever topic and he was able to solve like any exercise he encountered with that definition. He didn't even looked at examples or made exercises beforehand. He just read it and was able to solve any exercise regarding to that definition.

Is that normal? I really felt stupid.

On the other hand he was able to solve specific exercises in old exam papers which only 1-3 people were able to solve out of 90-140 participants.

Literally. Just read the definition once and was able to solve this task without prior exposure even if that topic was unknown to him.

Is this normal for people which did a lot of math or is this some kind of "talent/gift"?

>>8154635
f(x,y) is the annual snowfall at location (x,y). a) is the total annual snowfall over the county. b) is the total annual snowfall over the county divided by the area of the county, yielding an average snowfall at every point.

>>8154657
I'd say that's pretty average, maybe slightly above average anymore

Give a carpenter a tool, and he should be able to accomplish any task that requires that tool, and also be able to recognize when that tool is needed.

>>8154635
b is snowfall per unit area

>>8154654
What does it mean "total amount at a specific point". If you put a physical box of one square meter you would collect physical snow (measured by volume), but if it the box was smaller you would collect less (proportional to the are of base under constant downpour) if it had an area of a pin needle you wouldn't collect anything. What's happening is a limiting process similar to the "speed at a point" (the derivative). So you would measure it with height. (this is just dimensional analysis)

Tldr. amount of snowfall at a point is not fully precise, you have to work a bit to interpret it.

>>8154678
this cleared things up

thank you

>>8154635
look:
https://en.wikipedia.org/wiki/Multiple_integral#/media/File:Volume_under_surface.png

>>8150292
Where can I find textbook pdfs? A lot of the sci wiki stuff is broken.

/sci/, how many years left until I pay this off assuming I pay that amount every month?

>>8155093
nigga make an excel spreadsheet.

outside balance - payment
apply interest rate of 3.375/12 on what's left to obtain the next outside balance

repeat until you reach 0.

Oh you got conned btw.

>>8155093
used this
https://www.calcxml.com/calculators/pay-off-loan

Under the proposed payment terms it will take 54 more payments or 4.5 years to pay off the remaining balance. Interest will amount to $5,107. - See more at: https://www.calcxml.com/calculators/pay-off-loan?skn=#results

>>8155093
>>8155133

I also got 4.5 years, but when I called my bank to confirm they said I still had 11 years left on my loan.

>>8155159
???????

better ask for details, because that's not true.

>>8155159

What is the 1317.24 payment distributed as? You're paying interest, escrow, and the principal balance. It's essentially three payments in one. Look at your bill.

>>8155188

$404.92 for principal balance, $184.35 for interest, and $738.97 for escrow. Should it even matter? I mean, when all three are summed up and divided it should still go to 4.5 years to pay it all off. I think I have to go to the bank and see what's up.

>>8155193
Different anon and I'm not a taxonomist, but this shit is purposefully convoluted to look like less of a scam than it is, so it absolutely does matter.

>>8155193

You'll pay off your escrow at 4-5 months. You'll pay off your loan at 404.92 in 13 years, but I am guessing the payment for the principal balance per month will raise to hit the 11 year loan mark, so expect an increase to 500~ dollars. I am assuming, of course.

>>8150292
How good is being a Chem Major?
Is ChemE better and what's the difference between the two?

>>8155229
One gets you a paying job (ChemE) and one gets you nothing (Chem). Undergrad for pure sciences is just a waste of time unless you're going to go back to school for a Master's degree and a PhD.

How do I find good data /sci/?

I'm in need of a data set that follows the linear MIMO model (Y=HX+W).
Where can I find it?
How do I go about this process?

Any good tips?

How do you convince people that there are individuals out there smarter than Stephen Hawking? Or am I in the wrong here?

I told someone that statistically there are individuals with higher IQ, I told him that there are individuals who have accomplished as much as him and aren't recognized, I've tried to explain why he's well known, the person just won't budge

>>8155565
You don't because IQ is a retarded meme. Stephen Hawkings contributed a great deal to astrophysics, so he's a person of rarity and importance. Trying to get into "rigorous" quantification is memery.

>>8155565
Leave him/her in ignorance, don't waste time on groupies.

im currently looking into doing the MDPT in canada and havent done any math in 2 years
looking for a refresher on everything from grades 10-12 precalc and basic calculus and wondering if anybody knows a single place where i could find all this

>>8155572
I talked about IQ because I was just trying to find ways to convince him. He really didn't give me his definition of "smarter" so I just threw different things at him.

>>8155576
Khan Academy

Are either of these graphs planar?

I believe the first one is, but I'm not sure if I did the circle chord method correctly.

I do not believe the second one is. I can't even find a circuit that contains all of the points and it almost appears as if it contains the graph k5 which would mean it is not planar.

Is there any better way to check these? I never feel very confident using the circle chord method as I worry I might have made a mistake.

>>8155734
First one clearly is, second one is not, since by cutting a few edges you get a K5 complete graph.

>>8155737
So you can cut edges to show that k5 is a subgraph of an original graph?

And maybe not as elegant, but could you just say that the second graph has no Hamilton circuit because it has a subcircuit and therefore the circle chord method is not possible?

>>8155772
Yeah, the specific theorem you're looking for is a graph is planar if and only if it's subdivisions are planar. You can take subdivisions of the Peterson graph which show it's K5, which we know is not planar.

I have been reminded of the principle of salts lowering water's state change temperatures, but cant seem to remember the name assigned to this phenomenon. What is it?

>>8156181
Boiling Point Elevation.

Took me a minute to think of it. Had to consult my old text from years past.

>>8156187
I thought there was a person's name attached to it. I went through Lyman and LaChatelier realizing both were totally different things.

>>8155772
>So you can cut edges to show that k5 is a subgraph of an original graph?

No, that other guy was abusing terminology.

see: https://en.wikipedia.org/wiki/Petersen_graph#embeddings

>>8156191

Same, but I forgot you can derive it using Raoult's Law and Clausius-Clapeyron relation. So we might have confused it with that.

Are cosets just the fibers of a group (or ring) homomorphisms?

Also, should one first study orbits, inner automorphisms and conjugacy classes to truly understand them?

Their (cosets) definition (using the equivalence relation from here >>8151119 ) still seems unnatural /puzzling to me even though I've now been working with them for a while, and it's really starting to bother me

>>8156453
Or maybe I should say, the definition of the equivalence relation used to construct the equivalence classes / cosets is still confusing to me

>>8156457
Oh, and how does all of this stuff relate to the elementary algebra we learned in highschool?

>>8156453
Constructions are boring and you only need to worry about them long enough to know they exist. The only thing you need to know about quotients is that maps out of G/H are maps out of G which kill H.

>>8156517
Okay.. thanks. And when you say they kill H, does that essentially mean they treat it as the additive identity?

Eg we're destroying H = 12Z when we we mod out Z/12Z since we treat 12 (and all multiples of it) as 0?

>>8156651
Yeah I mean that H is contained in the kernel of the map.

Anyone wanna recommend discrete math and numerical analysis texts for programmers? The ones I've found are meant more for math majors and have unnecessary rigor.

I'm taking summer session discrete math, and the professor got swapped out. Now stuck with one who rambles, makes mistakes, and generally wings it through his lectures, in addition to not knowing anything about the applications. I'm transferring for mechanical engineering, so I was just taking this for fun. Debating whether to even stick with it for the sake of padding my gpa if its going to be boring as hell.

>>8150292
How do I set up this problem? I'm confused because t is a part of the angle.

>>8156731
Google this

mathematics a discrete introduction pdf

Choose the first thing that comes up (the PDF to the third edition)

>>8152863

If you're used to math being calculating things, you're going to be disappointed by what "rigor" actually ends up meaning. Rigor ends up being mostly just formal semantics, which really doesn't have much of an exciting geometric or numerical counterpart, other than inequalities and inclusion/exclusion.

However, if you still want to try it, if you brush up on some basic grammar, formal logic (going back as early as aristotelian logic, if you want), and philosophy and history of math, you'll be better prepared. Don't shy away from reading the actual original documents in which abstract concepts are first introduced if you're having trouble "getting" something that seems abstruse. Also, don't be afraid to use analogies and "concrete" examples to explain abstract concepts. I see people get stuck on abstract concepts a lot because they don't allow themselves to refer to the concrete thing which the concept was "abstracted" from. They think it is cheating or something. Use whatever tools you need to. Comprehension should be your highest priority.

>>8156746
looks unpleasant to solve
I'm not sure but I think you use the cooling law
T(t) = external temperature
B(t) = temperature of body
dB/dt = k(T-B)
dB/dt = k((60-15sin(pi*t/12) -B) then solve

>>8156746
Missing some info. How do you calculate [math]T[/math] of the body given [math]T[/math] of the warehouse?

>>8155565
the person you're arguing seems really dumb and unlikely to change his mind, no point in arguing with him

people specialize in different things and he seems to value astrophysicists in particular unreasonably high because he fell for some meme

>>8157007
Thanks thats defintley the first step
>>8157020
I think because that's the room temperature in the equation for newtons law of cooling that >>8157007
remembered. so i guess i can just call it m in this equation dT/dt = k(T-m) i guess the problem now is actually integrating it.

>>8150787
For applied purposes? All you need is applied prob/stat I bet.

The actual theory? I doubt it, you need the whole works of analysis and measures to even begin.

>>8150354
no such thing

>>8152362
>>8152282
I'm really hoping this is bait but in the off-chance that some lurking underage is reading this and for some reason believing retards on the internet:

If you think that a PhD is something you grab for each subject you're interested in, you have no fucking clue what a PhD is. I don't know where people got this impression that "really smart people" or even "really motivated people" earn multiple PhDs, it's insanely absurd. See:
http://academia.stackexchange.com/questions/17232/is-doing-two-phds-a-good-path
http://academia.stackexchange.com/questions/34423/is-it-sensible-to-do-two-phds-simultaneously

As for multiple degrees during your Bachelor studies -- it really doesn't fucking matter. Sure you can triple major and 1) take no upper level/grad electives and 2) perform no significant amount of research, aka the stuff that actually makes you a competitive PhD applicant, all while overloading your schedule. But I wouldn't fucking recommend it -- for the reasons I mentioned, and also because no one will be impressed. Major in what you're most interested in, take electives in other fields that you have somewhat less interest in (but still want to learn about).

For what it's worth, my B.S. is in physics, and quite bare really, since I switched from engineering halfway. Right now I'm doing my PhD in quantum complexity theory. I'm surrounded by theoretical CS and pure math people all the time, as is typical of the work I do. I didn't take any proof-based math courses in undergrad, I didn't take any real comsci classes. Yet my work is all founded on the ideas of theoretical comsci and numerical analysis; I write papers in the traditional theorem-lemma-proof style.

My point is, it really doesn't fuck matter, especially if you're interest is in the mathematical sciences. If you don't know something, you pick up a book and a lot papers. How you show you can do that is through undergrad research, not multiple degrees.

>>8156746
>those non-[math]\verb|\left(|[/math], [math]\verb|\right)|[/math] delimiters

>>8157075
>probably made in microshaft word

>>8157075
I can't be the only one who corrects this on Wikipedia

i'm working on a larger integration problem and don't quite know how this works but it's relatively simple

if arcsin(e^x) = θ
2arcsin(e^x) = 2 θ

how do i calculate sin(2arcsin(e^x) and why is it 2e^x root(1-e^2x)

>>8157075
>using \frac (or god-forbid \dfrac) in inline text in the first place

>>8157091
oops

>>8157093
\frac should auto-format to \tfrac to look like it's inline: [math] \frac{1}{2} [/math] test

>>8157091
Short answer: Double Angle formula and Pythagorean Theorem
Longer answer
think of it like a right triangle with the 3 sides
[eqn]\sin(\theta)=\frac{e^x}{1}=\frac{opp}{hyp}[/eqn]
[eqn]a=adj,b=opp,c=hyp, a^2+b^2=c^2,b=1,c=e^x,a=\sqrt{1-(e^x)^2}[/eqn]
[eqn]\sin^{-1}(e^x)=\theta=\cos^{-1}\frac{adj}{hyp}=\cos^{-1}{\sqrt{1-e^{2x}}}[/eqn]
[eqn]2\sin^{-1}(e^x)=2\theta, \sin(2\sin^{-1}(e^x)=\sin(2\theta)=2\sin(\theta)\cos(\theta)=2 (e^x)(\sqrt{1-e^{2x}})[/eqn]

>>8157128
thanks a lot for the explanation anon
i ken i ought to memorize the identity:
sin(2θ)=2sin(θ)cos(θ)
cheers

This is babby's first physics but everything on google just points me in a direction I already tried.

Am I correct in assuming that the only tangential force acting on a swinging pendulum is the tangential component of gravity? I'm trying to find its tangential acceleration, which I would assume would just be findable through newton's shit: mgsin(θ)=ma_t, where θ is the angle with respect to the vertical. Drag is not applicable here since I have no way to find the cross section area.

My major is CS but I also want to take bussiness as a minor. Is that a good idea? Will I have better job offers when I leave college?

>>8157191

You are asking us to predict the future, which is logically impossible. Any answer, therefore, would be misleading at worst, and dangerous at best. We scientists concern ourselves only with questions that are epistemologically sound.

>>8157191
might help a bit but it's nothing crucial

>>8157191
It's not a bad idea. Take class which interest you.

>>8157068
not bait.
im not interested in the degrees persay, just the knowledge of those fields. you do have a point

>>8157235

It's not just me who has "a point," that was sorta the reason for those links. A PhD is not about gaining knowledge in fields -- you can pick up a book, read a paper, and talk to professors for that. A PhD is for *doing* quality, novel research: creating new knowledge in a field. More importantly, the PhD is training to show that you are able to do so. If you want to make contributions to mathematics, physics, and computer science afterwards, well I won't say you can't (even though it is essentially impossible to be a polymath nowadays). What I am saying is that you don't need multiple degrees to do so.

>>8157197
> not taking probability into account

>>8157275

Probability is still logically unsound, because it requires an artificial model which by nature has no connection to reality.There is nothing wrong with building models, but the fallacy lies in extrapolating a probability computed internally to a theory to a statement about the physical world.

>>8154635
>Erie County, NY
Are you in Buffalo, at UB? I'm doing nothing this summer and I just got a vehicle wants to be friends??

I'm Electrical Engineering

>>8156746
>After a very unpleasant Valentine's Day
Nobody else noticed that?

How do I get over test anxiety?
I'm currently in Calc II; it's 1am and it have my first exam at noon.
I haven't experienced anything as intense as this and it's interfering with my ability to study.
My test is covering all basic integration, u substitution, integration by parts, trig integration, trig substitution, Partial Fraction Integration, special substitution and rationalization, improper integrals, arc length over an interval, surface area of a revolution, satisfying first order Diffy Qs, and both general/particular solutions of first order Diffy Qs

Honestly none of the material individually seems too hard, but the sheer volume of material that is being covered is overwhelming me.
Help /sci/ how do I just relax?

>>8157316
life is based on logical conclusions made from prior experience or knowledge learn somehow. Nothing in life is concrete factual. So I ask you with no malice but rather with a open mind.

>>8157386
You're in America but you still have finals? The fuck? How are classes still going on?

>>8157401
Not finals. I took Calc I in the spring and I'm currently taking Calc II in this summer semester.
Also this is just a regular exam, but holy shit I've never had a test that covered so much material.

>>8157355
you still need to calculate the time of day, not the day of the death

>>8157404
Oh I see. I never took important classes over summer, just the bullshit core humanities classes. They did manage to pack a ton of material per week, jesus christ.

If your problem is relaxing, idk man just take your mind off it for a bit. When you go to study/think about it don't treat it like some do-or-die situation.

Is it a stupid idea to have a multimeter permanently attached to batteries? I've build a portable speaker system powered by some 12V batteries and cant really find a way to measure their capacity so I was thinking about having a multimeter attached so I could read whenever the voltage drops below 12V

Any other way to reliably know when to charge the batteries? They have an indicator but they're also inside a locked box/cabinet and kinda a hassle taking them out all the time to check.

>>8157447
you could hook up a probe to the indicator

>>8157166
> Am I correct in assuming that the only tangential force acting on a swinging pendulum is the tangential component of gravity?
There are only two forces on a pendulum: gravity, and the tension in the string. And the tension is perpendicular to the tangent, so it can't have any tangential component.

>>8157464
The indicator isnt actually a readout, it looks like a LED that doesnt light up but switches to black from green if you need to charge and is embedded in the battery housing

I took an online test, the right answer gives 2 points the wrong answer -1, not answered question 0 points.
I marked 5 out of 6 answers and ended up having 3 points in total.
How is this possible? I have a hunch that this test is rigged or bugged and my actual answers are not submitted.

>>8157490
Nevermind that,
[math]2x + (-1)y +0z=3 , x+y+z=6 , x+y=5[/math]
It's not possible and it's bugged.

>>8157424
Friendly reminder of why really runs the show

>>8157946
t-rexes aren't that dangerous, you could easily contain it/defeat it with modern equipment and weapons, especially a newborn t-rex

What are some good sources to learn how to illustrate circuits on paper and then translate that to a breaboard or a protoboard.

I feel so impotent whenever I see videos of people just understanding these lines and symbols and I just dont understand how they got to that.

I did took some circuit courses but all of that was just simple stuff without many complications. I want to go from ''Solving this problem of X type of circuit'' to actually making stuff on my own.

Please help.

>>8158045
> dat peach bottom of tracer
muh dik

>>8158045
>tfw no gf

Realistically speaking is one month enough time to seriously understand and finish calculus 3? I signed up for an accelerated online class at my school but I'm having second thoughts. I know a lot of /sci/ like to pretend that they're 100% driven hard workers but anyone with experience in a course like this have any input? Should I just sign up for the 3 month long one instead?

>>8158051
hardest metal?

If I took 5 years to graduate with an EE degree, will it be that big of a defect in my resume? Am I just overestimating the impact of the time it's gonna take me to graduate?

Backstory: got accepted to the school i wanted, but not for the major I wanted (EE). To makes matter worse, I slacked big time freshman year but managed to somehow get accepted into EE, and been picking it up gradewise.

>>8158051
>>8158067

Pls help guys. I too want to bury my face on tracers ass, but thats not important right now!

would a set that contains all set have

1) countably infinite order (aleph-null)
2) uncountably infinite order (aleph-one)
3) something else? (another aleph)

>>8158152
More like aleph-(-1/12) bro

>>8157946
yeah, only humanities could possibly come up with why 'this might be a bad idea', hooray humanities, they are so useful and employable and worth anything

Do you guys choose courses with professors that you know are good? Normally I don't give a shit who the professor is, but next semester I'm taking Real Analysis next semester which I heard is really hard.

One section is taught by a prof that taught Discrete Maths and I really enjoyed and learned a lot from him. Problem is that it conflicts with another course that I really want to take, but isn't offered often (NLP).

The other section's prof is unknown at this point. Probably going to be a grad student. This section has no problem with the NLP course that I really want to take.

Which section should I pick?

>>8158045
First off, you need to understand the core theory of the type of circuits you're dealing with (i.e. analogue or digital; the two have very little in common).

For analogue, you need at least Ohm's law and Kirchhoff's voltage and current laws. You need to be able to do algebra for anything involving feedback (e.g. solving systems of simultaneous equations). Signal processing has a large amount of theory behind it (second-order linear ODEs, Laplace transform, Fourier transform), but for the basic stuff you can get by with just being able to use Kirchhoff's laws with complex voltage, current and resistance.

Digital doesn't really need any of that (for interfacing, you just need to know how to use transistors as switches). It's basically combinatorial logic (boolean algebra) -> asynchronous sequential logic -> synchronous sequential logic.

>>8158074
How did you feel about calc 2? 3 is more of the same, just a little harder to wrap your mind around on account of the geometry. There's a few more rigorous theorems dealing with surface and volume integrals towards the end but if youre comfortable with everything else its not bad.

>>8158074

It's not too bad. Like >>8158317 said, if you did well in Calculus II and feel comfortable then you will do fine.

It is basically calculus I and II with a third dimension.

How do I get research experience and reference letter for graduate school? Canadafag here, only my last two years matter anyways, in chemical engineering.

My GPA is very poor due to a horrible first three semesters, but I got straight A's last semester after putting in some work. Can I just walk up to my profs and ask them if they want some slave labour?

I'm really not stupid, I just had some very difficult personal issues and extenuating circumstances...

>>8158403

Basically just ask every professor you can for research. There is no magic trick to it. Just write a good email and say you are interested in their research and want to go to graduate school / looking for a mentor.

Most of the time they don't really care about your GPA (in regards to taking you on), but they will ask you when they hopefully help you make a list of schools to apply to.

Would an undergrad in computer engineering with a minor in business be okay? That way if I fail as an engineer I can at least get into finance?

>>8158566
Minor in statistics instead

Could someone please show me how I would prove this? The question feels quite ambiguous.

>>8158157
Why do serious questions often get meme responses on here?

Any engineers that took the FE? I'm curious to know your opinion on it.

A lot of places I've searched assume it's 100% reference manual, but I'm not so sure

German here. When I was a child I was blonde but suddenly my hair turned to be dark brown. What could be the reason for that?

I want to get into particle physics, where should I start, I read a bit about the fundamental particles

>>8158731

Why does everyone want to be a Particle / Theoretical Physicist? Just a trend I noticed, personally I think Biophysics is cooler, but that's just me.

Major in Physics and Math, do really well, study hard. Do research in the department, get good letters of recommendation from your research adviser / professors. Try to get the CERN internship during the summer and do summer research at other better schools, they're called REU's. Or just stay with your lab during the summer to help get them sweet publications.

Then apply to the best graduate schools you can. By then you will know what to do from there.

What are people working who went to university to study philosophy? What exactly are you doing at that major?

>>8158754
I like bazinga guy from big bang theory :-D

>>8158754
>personally I think Biophysics is cooler, but that's just me
I must say it sound interesting to me, too. But isn't it mostly just statistical physics? Not very fond of that,
And particle physics kinda gets you close to knowing "the stuff the world is made of" (as far as "knowing" goes in physics), so there is the appeal I guess.

>>8158719
it's those lederhosen

http://www.livescience.com/34827-towhead-blond-kids-blondes-go-dark-brunette.html

>>8158783
>Biophysics

It's pretty broad, a lot of people don't know much about it.

>Particle physics

I guess that could appeal to some, but I never found interest in that, so I decided to major in Chemistry.

I do chemical physics / biology now which is basically physics principles applied to problems in biology and chemistry, I focus on biomedical aspect though.

What is an electrolytic battery? I have to make one but I can't find anything about them

>>8158866
If you have to make one, I assume you are in a chemistry class or somesuch, and if you don't know how you have been paying absolutely no attention.

Electrolyte, cathode, anode.

This was never really explained to me in university and high school

Why do we take the limit of an infinite series as its sum? Doesn't it go against the definition of an infinite series to even have a sum? How does this math even work?

Why does 1/2, 1/4, 1/8, ... sum to 1? Or is it just an approximation that 0.99... = 1?

I have tried looking for videos but all I get is basic explanations of series, I don't need to know what they are I want to know WHY they work this way. It seems contradictory, why does Zeno's paradox not hold true?

>>8150292
There was a Logic study group on Slack floating around, could someone send me an invite?

axhodges@gmail.com

>>8158896
> Doesn't it go against the definition of an infinite series to even have a sum?
Not if the series is convergent.

> Why does 1/2, 1/4, 1/8, ... sum to 1?
1/2 = 1-1/2
1/2+1/4 = 1-1/4
1/2+1/4+1/8 = 1-1/8
...
1/2+1/4+1/8+...+1/(2^n) = 1-1/(2^n)
Clearly, the limit is 1.

> Or is it just an approximation that 0.99... = 1?
It's not an approximation; those are just two different notations for the same number.

> I want to know WHY they work this way.
Limits. A series is simply a type of sequence. Some sequences have a limit. E.g. any geometric series with a ratio less than one has a limit.

s[n] = a+a*r+a*r^2+...a*(r^n)
r*s[n] = a*r+a*r^2+a*r^3+...a*(r^(n+1))
= s[n]-a+a*(r^(n+1))
=> (1-r)*s[n]=a-a*(r^(n+1))
=> s[n] = (a-a*(r^(n+1)))/(1-r)
If r<1 then r^n tends to zero as n tends to infinity and the sequence converges to a/(1-r)

>>8158896
>It seems contradictory, why does Zeno's paradox not hold true?
The same reason that Zeno's paradox doesn't stop motion from being possible in the first place - it's not a real issue, it's a difficulty in conceptualization.

>>8158937
>It's not an approximation; those are just two different notations for the same number.

I think this is my problem with this, I understand limits very well. Just don't understand how you can get an answer of 1 when the series never actually reaches 1, but rather 0.99...

How can we say with such certainty that two different numbers are the same thing? Maybe I'm just being dense, sorry.

>>8158946
>How can we say with such certainty that two different numbers are the same thing?
Because there is clearly no number between the two, hence there is zero distance between them.

>>8158946
> when the series never actually reaches 1, but rather 0.99...
Those are different representations for the same number (normally written "1").

> I understand limits very well
Everything you've posted so far suggests the opposite. If you know the formal definition of a limit, it's trivial to prove that the limit of that sequence is 1.

>>8158947
the axiom of choice allows me to choose a number between the two since they have different decimal developments.

Where does one buy bench DC power supplies?
They are available from chinese sites but I want to compare prices

>>8158979
No it doesn't. You could invent a new set with whatever rules you want and apply the axiom of choice. But that's really not what we're talking about here.

>>8158896
you can always add the next fraction, you can get arbitrarily ("infinitely") close to 1, if you're really really close to 1 you can still get closer to 1, but you can't get higher than 1, so the limit is 1

Speed is relative, except at c. A photon is measured to be moving at speed c in all reference frames. Further, an increase in relative speed slows the passage of time for that frame of reference relative to the "outside" frame.

Despite the impossibility of physically doing so, let alone making measurements to figure out how to do so, suppose one could slow towards zero "absolute speed" - relative to spacetime itself. That is, canceling out the motion inherited from the Earth, from the Sun, from the galaxy, from the local supercluster, and from any larger features. Would this accelerate the passage of time relative to the Earth? If so, would there be a limiting factor similar to approaching c - where the rate of passage of time increases without bound as you put more energy into attempting to cancel out all forces that would stop you from achieving this?

Has such a thing been considered since the inception of special/general relativity? I expect it to be nonsense, but is there a term to search?

>>8159096
Go properly study basic relativity, dude.

>>8159106
After DiffEq, brudder.

>>8158979
> the axiom of choice allows me to choose a number between the two since they have different decimal developments.
Wrong. There is no "they", only "it". Being able to write it in more than one way doesn't change that. "1" and "0.99..." are no more distinct than "1" and "01". You can't choose a number "between" 1 and 1.

>>8159115
You dont even need any calculus to understand the garbage youre spewing.

>>8159120
but I can.
and I will.
I'll even call it wone.

hi, high school student here in Aus here nearing final year. I am doing well in school and will be 1st generation to be in Uni. Growing up parents noticed I was smart and expected me to support the family financially, however I am still pretty interested in going into academia which obviously will not generate as much money as going into an industry. Anyone have a similar situation and/or have thoughts? Am I too naive?

I've discovered an error in a two years old paper which renders much of their results incorrect but which can be fixed trivially - most likely it was just an oversight. Still, some newer work has cited and used the incorrect data since then.

I was thinking of just e-mailing the original authors and leaving the fix to them, but my advisor says I should publish the issue along with a fix as a Short Communication paper instead, so that "there's a paper trail and people amending things know what to cite, otherwise the story in the literature will be incomplete".

Thoughts?

>>8159459
your advisor is right

>>8159369
money is the key to success and happiness in life. try finding a career/business path where you still deal with the subjects you're passionate about. and for example, disney/pixar publish research papers all the time.

>>8159464
I guess the thing that's making me think twice is the fact the error isn't a major issue but rather a "we forgot to do one obvious processing step on part of our data and now half of our results are stealthily borked" issue.

Also the fact it was a big paper with several Big Name in a Small Field authors and I hesitate to piss them off.

All I know for certain is that I wouldn't want to be the grad student who made the error.

>>8159474
Why do you care? Do you think they would do you the same service if you fucked up and there was a chance for another paper out of it?

>>8159482
I care because I'm starting to look for postdoc positions and it's probably a bad time to piss important people in my field off. There's over a thirty names on this thing and I recognize quite a few of them.

>>8158622
You just have to show f(-1) and f(1) have opposite signs. This is the definition of a bracket of a root.

Is it possible to define the ordered pair in set theory such that [math](A,A) = A[/math]?

(To the best of my knowledge: the usual Kuratowski definition is [math](A,B)=\{ \{A\}, \{A,B\} \}[/math] which yields [math](A,A)=\{\{A\}\} \neq A[/math]. The defining property of the ordered pair is that [math](A,B)=(C,D)[/math] iff [math]A=C[/math] and [math]B=D[/math].)

>>8159501
But what's the definition of a "proper bracket"? That term doesn't show up in any of the (few) references I've looked at, so the poster needs to quote the definition which the question uses.

The fact that f(a)*f(b)<0 for a<b doesn't automatically mean that there's a root in the interval [a,b]. There may be a discontinuity or singularity, so you also need to know that the function is continuous in that range (which is trivial in this case). And even then, you don't know that there's a single root; there could be any odd number of roots.

>>8159542
https://en.wikipedia.org/wiki/Bisection_method#The_method

>>8150292
What do you guys think about the hypothesis that says that there are constant tumors forming in your body but only those that can reach or induce the development of blood vessels to themselves actually become dangerous?

>>8159556
maybe

>>8159560

but how much... maybe?

total maybe, or maybe maybe?

>>8150292
Ok, so i just started a Thread at /b/ and basically got no useful answer so my question should meet this thread quite nicely.
I was just wondering about the so called greenhouse effect and how solar Power is considered "green".
Solar Pannels are hard to Produce maintain and all that stuff and overall a pretty bad way to produce energy in comparison to most alternatives.
Butt the thing that annoyed me the most was always that Solar Panels basically work Exactly like green house gases.
They increases the amount of energy that is absorbed into the Earth/Atmosphere/whatever.
Can someone please explain to me why Solar energy is even a thing or considered green, when its whole concept is to do the the same thing greenhouse gases are so hated for?

>>8159591
Alright you seem a little lost so we are going in from the start :
The problem of fossils-based energy is the by-production of so called "greenhouse" gases (mainly CO2, other exists). What is the problem with them ? They go in the atmosphere and act as great heat traps and emitter, meaning that they absorb way more infrared light than they let go into space, and they even re-emit some of that light.
So basically, when we produce energy with fossils fuel, we produce more gas that trap more heat, the spiral goes on and on.
Now solar panels : Yes, producing them is not that green. But they work by "just" trapping the energy from the Sun and transforming it into electricity. They don't reflect that much, and even then it's no biggie since reflection is not greenhousing. They are green in the sense that there is no byproducts able to harm the balance of the energy flow between the Sun and Earth.

>>8159551
Doesn't use the term "proper bracket" anywhere.

>>8159542

Proper bracket just means bracket, as in "first, make sure you have properly bracketed a root."
From the problem statement, we are given that there is a root in (-1,1).

>>8159591
>They increases the amount of energy that is absorbed into the Earth/Atmosphere/whatever.

Yes but that energy is not wasted into heat but transformed into electricity that we redirect to our needs.

So, does it means that you're adding energy to the Earth system? Yes, technically. And even like that you would need to to some planetary engineering like filling an entire(or several) country with solar panels to start noticing something in the slightest.

The problem with renovable technology is usually that fanatics can't acknoledge the fact that any human intervention in nature is intromisive by itself and will create unwanted changes(like birds putting nests on aerogenerators), and since they usually talk about a total substitution of energy based around liberating that energy from carbon, the ammount of infraestructure required to do so, would create several "forests" of solar power plants.

If you're arguing with someone more moderate, they have to acknoledge nuclear power as a way to stop this problem.

Anything else related to "they will surely improve technology!"should be met with the fact that extracting energy from the sun(even wind and currents are affected by the sun) is inefficient since we have an atmosphere that steals a huge ammount of solar energy and so, we will always require faraonic constructions for total "green" energy.

>>8159623
proper + bracket
"correct" bracket

>>8159637
Nuclear energy seems the best choice we have to power huge nations that can afford the cost of security, waste management, improvement and maintenance.
Alternatively, solar panels don't need to all be concentrated in one region, put a few on each roof and you have the same energy produced. They are a good system for less needy nations or for small/isolated communities.
Using fossils fuels on a small scale (generators for example) is a good alternative with little to no negative effects.

There is no big winner in energy production, we need multiple tools for multiple problems.

>>8159652
There is not nearly enough nuclear fuel to power the world for a significant length of time

>>8159601
I think you missed my point.
Also the way you explained global warming was kind of condescending and unnecessary.
The basic point is that greenhouse gases cause a bigger part of the radiation of the sun to be absorbed instead of being reflected by our system.
My point was that solar Panels also increase the amount of energy that is absorbed since less energy is reflected by the surface of the earth and more is absorbed/converted .
Thereby Solar pannels would have a similar effect as greenhouse gas.

>>8159656
source?

>>8159656
You forgot fusion.
>>8159657
That's like saying photosynthesis create greenhouse effect, seeing everything in energy misses the pratical aspect of it.

>>8159637
Well solar Pannels are only about 30% efficient in energy conversion so the most energy is converted into waste heat. Also the electricity will eventually be converted to waste heat.
So i guess i would need some numbers on how much this actually effects our system and the amount of "energy intake"
Overall a reasonable answer thou, thanks.

Is there some sort of flowchart around that shows the progress of mathematics? I mean like:

Algebra --> Pre-Calculus --> Calc I/II/III --> ODE

I just want to know the proper route to study in.

>>8159662
>>8159667
Well reread what i wrote if you need to. I said similar effect. And yes if want to cover the energy consumption of the earth with solar panels you would basicly cause more energy to be absorbed by the earth. Which would be in relation to the energy consumption(Electricity by humans) of the earth.
Now the only interesting thing would be in what relation that would stand to The amount of energy Absorbed due to the Greenhouse effect.

>>8159657
i think solar panels are a horrible meme

but

the point is that when solar panels absorb energy, it's useful energy

when greenhouse gases cause energy to be absorbed, you can't use that energy

>>8159678
google history of mathematics, try wikipedia and some other links, should give you a nice overview

>>8159514
If (X,X)=X, then with X=(A,B) you get ((A,B),(A,B))=(A,B), and also ((A,A),(B,B))=(A,B), therefore ((A,B),(A,B))=((A,A),(B,B)), but as you said, the defining property of the ordered pair is that (A,B)=(C,D) if and only if A=B and C=D.
So the answer is no.

im... I really need help with this

f(x) = arc cos (log x)
find f (1/10)

I dont understand how, this should be a real easy and simple thing but something does not click

arc cos (log 1/10) can be rewritten as:
cos [some angle] = log 1/10

now I think I should find a log of 1/10 but I just dont get it, normally logarithm has a base, a value, and what it's equal to, but this logarithm does not

I dont get it, can someone please help?

>>8159769
Depending on your country, log without a base either means the natural logarithm (base e, also denoted with ln sometimes), or the base ten logarithm. I assume it's base ten in this case, since then log(1/10)=log_10 (1/10)=-1 and arccos(-1)=pi, while arccos(ln(1/10)) is some horribly ugly number.

>>8159774
yes yes yes, thank you! solution is pi, but I still dont quite understand how

i will look up how is log sub 10 base 10 equal to minus 1, something about it is confusing me, i got 1/100 for some reason when trying to find the log and than tried to find cos of 1/100 while I needed to find cos -1....
thanks btw, but can you also explain how is the log -1 instead of 1/100

>>8159774
thanks, got it, my understanding of logarithm failed

>>8159780
You know, if log_a (b)=c then a^c=b, like log_10 (100)=2, since 100=10^2, so since 1/10=10^(-1), log_10 (1/10)=-1.
Maybe you don't know that 1/a^n=a^(-n).

>>8159786
yeah, my basic math (arithmetic in english?) sucks, this is why I am struggling with analysis right now

>>8159786
one more thing, how is arc cos (1) equal to pi/2?

arccos(1) is the same as
cos[angle]=1
cos is x on the unit circle, and on the unit circle, when x is equal to 1, cos is 0 or 2pi, not pi half, it would be pi/2 for sin, but it clearly says cos, not sin

is this a textbook error (unlikely), or am I making a mistake somewhere here (more likely) ?

>>8159793
Why are you taking Mathematical Analysis if you don't know that 1/a^n=a^(-n)?

>>8159803
because I need it for my first year of basic academic studies for a physics degree and basic arithmetic can be learned in a day or two, I already passed it in highschool, just need to re-learn it, and function analysis, finding limits and all that, it cant be that hard to do either, I just need to practice
I am allowed to pass problems exam and than I am allowed a few months to also learn to prove things

>>8159800
>how is arc cos (1) equal to pi/2?
It's not. arccos(1)=0, since arccos is defined so that if cos(a)=x then arccos(x)=a AND -pi/2 < a < pi/2.

I'm working on prerequisites to get into a nursing program, but I love this bio stuff. Professor is offering for me to join the research department. Should I do it, even if I don't plan on going biochemistry major till I have my BSN (which will be about 3-4 years from now)?

>>8159817
Sorry, I meant -pi/2 ≤ a ≤ pi/2.

>>8159817
>>8159820
arc cosine is normally defined as having the range [0,pi] (that's how C defines acos()).

cos() is symmetric, i.e. cos(-x)=cos(x), so if acos() used the range [-pi/2,pi/2] it wouldn't work for negative arguments and the result would be ambiguous for positive arguments (either a or -a would be equally valid).

asin() is defined as having the range [-pi/2,pi/2].

>>8159884
yeah sorry, I looked at the wrong row in wikipedia, pic related

>>8159757
Well shit. Thanks

>>8159946
>>8159757
Sorry, I fucked up a minor thing though, I meant that the defining property of the ordered pair is that (A,B)=(C,D) if and only if A=C and B=D (I originally wrote A=B and C=D).

>>8159814
How does one choose to enter the field of physics while not knowing basic arithmetic by heart? I think that if that basic math didnt interest you enough to cement itself when you first learned it, you will struggle enormously when you get to upper division physics. Make no mistake physics is very heavy in advanced math, enough so that it obscured the physical for me and killed my interest.

How much better would our life become if you made brains work via light (i.e. photons) instead of electricity?

>>8160077
I guess our brains would be smaller (more processing dense) and we would have better reaction times. Otherwise, processing power is evolutionary - wouldnt make much difference.

>>8152382
i'm shitposting

>>8160077
Signal propagation in nerve cells isn't purely electrical but electrochemical. Nerve signals at something like one third of the speed of sound.

>>8160161
*Nerve signals propagate

>>8159489

you're deluded. they're going to appreciate the correction, they're not going to get mad at you.

Is it possible to write a "chemical equation" type of "equation" that is impossible to balance? Of course such a thing would not exist chemically IRL, but mathematically is it possible?

>>8160624
I can't be fucked to do it because I'm out of practice and my curiosity is satisfied, but you could set up systems of equations for different molecule configurations with integer variables, row reduce them, and see for exactly what ranges of those variables the system is inconsistent. Those ranges would correspond to unbalanceable equations.

Is pic related good for a beginner ?

>>8160846
How beginner? It isnt laid out like most math and science texts, which makes it a bit difficult to read and comprehend. If you've already had electrical theory in the physics sequence and have covered basic rc circuits, kirkhoffs rules, and the application of calculus, its probably fine. You may find a lower level book easier to understand, though.

>>8160862
>most math and science texts
I should say modern texts, since there are plenty of older texts written like it targeted at those building from an established understanding.

>>8160862
I know 12th Grade's maths and physics equivalent, so rc, kirkhoffs and calculus are fine

What would happen if someone had their Adrenal glands removed? How would they behave?

>>8160161
Right, hadn't thought about that. So in case we want a photonic brain we must actually also turn all chemical synapses into synapses by contact?

Why would any engineer or computer scientist stay in academia instead of joining industry? My CompSci prof. makes 75k a year and he has a PhD.

>>8161394
You'd need a whole new, completely different system and how it would work depends on how it's designed.

Nerves aren't like wires conducting electricity which you could conceptually replace with an optical fiber equivalent. Even with "electrical" synapses rely on building membrane potential through ion transport, it's still primarily a chemical process.

>>8161670
> Why would any engineer or computer scientist stay in academia instead of joining industry?
Not having to deal with MBAs is probably the biggest reason.