/sci/ - Science & Math

Is there any community college in california around LA/San Diego that offers Physics I and II combined in one semester? I want to take out both courses in one semester.

>This course is a calculus based study of statics and dynamics of particles, solid bodies, along with fluid mechanics and wave motion. It is designed primarily for students who plan to major in physics, engineering, chemistry, mathematics or life sciences. It is also designed for pre-medical students.

What's a good Physics book that covers this? The college book is complete shit.

Is pic related meaning that everything is mod p?

What is the saying "Never complain, never explain." supposed to mean?

Do EE majors ever use the various methods to solving curcuits?

>>7682389
I don't think so, isn't Physics I a prerequisite for Physics II at community colleges?


My question:

My TAG got accepted to UCI but sadly, I withdrew from a course I need and won't be able to finish the requirements to transfer by spring due to needing 6 classes now. My major is computer science, so obviously UCI is a great school for it.

Should I just transfer into a CSU? I was thinking Fullerton or maybe LB. Or should I wait until 2017 to be at UCI? This is my 3rd year at CC i dont want to be a 4th year student there.

>>7682386
>>using namespace std;
>>not using std::cout instead

d*e mod φ(n) = 1
given that i know what e and φ(n) is, how do i find d?. I've been trying to understand the extended Euclidean algorithm for a while now but i guess math is just not my forte. Can someone dumb things down for me?...

>>7682682
What class is this for?

>>7682721
Information Security. We are supposed to research more into a specific field we are interested in. Since i'm interested in crypto i've decided to learn more about RSA. finding d is required to generate a key

[math]\mathrm{If} ~ w = \lambda a ~ \mathrm{for} ~ 0 \neq a \in \mathbb{R^3} ~ \mathrm{and} ~ 0 \neq \lambda \in \mathbb{R} ~ \mathrm{is,~ then~ the~ following ~applies~ for~ every} ~ b \in \mathbb{R^3}, (w,a \times b)=0.[/math]

I am not quite sure about this statement, it is either true or false. I believe it is false because the cross product of a null vector and a vector [math]a \neq 0[/math] does not mean the result will be a null vector?!

>>7682682
>>7682724

long a1 = fi;
long b1 = fi;
long a2 = e;
long b2 = 1;
long a3 = 0;
long b3 = 0;
long multiplyVal = 0;
while (a3 != 1)
{
a3 = mod(a1, a2);
multiplyVal = Convert.ToInt64(Math.Floor(Convert.ToDouble(a1) / a2));
b3 = b1 - (b2 * multiplyVal);
if (b3 < 0)
b3 = mod(b3, fi);
a1 = a2;
a2 = a3;
b1 = b2;
b2 = b3;
}
return b2;


oh boy wrote it out in c#. Finally got it after watching some youtube vids. a3 and b3 are unncessary though i think...

>>7682669
wait so why cant you take the course in the spring? dont know much about UCI other than it sucks dick and bunch of asians go there, but CSUF has a decent program. I dont know about LB either sorry. I go to CPP

just try to get into UCI man, itll be easier and better for you in the long run

also, UCI is fucking shit

linear algebra book for people who need a hand?
I heard strang is good, is this true?

>>7682636
You're modding out the ring of integers by the principal ideal generated by p.

If that doesn't make sense, pull out your copy of Artin and read the section on quotient rings.

>>7682986
I really like this one. If you prefer physical then you can get it on Amazon as well.

http://joshua.smcvt.edu/linearalgebra/

>>7682669
It is a prerequisite, but I would think that the first 8 weeks is physics I while the last 8 weeks would be about physics II. I couldn't find a CC that did this.

>>7682724
Could something that big actually be built? Even if it's in space, it's as big as mount fucking everest, and you know, the square-cube law and all...

what did I do wrong?

I have to prove the following with the Mean Value Theorem and I have NO FUCKING IDEA how to do it:

[math]e^{x }> 1+x[/math]

For [math]x>0[/math]. Can someone point me to the light?

How does adiabatic heating work? If no heat is transferred to a system, how can the temperature increase if dQ=MCdT?

>>7683486

Nevermind, guys. I figured it out. I forgot to carry the 5 to the f(0). After I did that then the rest was smooth sailing. Boy is my face red that I made such a simple mistake.

Idk how to maths, how to maths? pls help, i'll fail college

>>7683584
Work transfer.

Why can't an index variable appear more than twice in a single term in Einstein notation?

>>7683557
Write the inequality as
[eqn] \frac{e^x - e^0}{x} > 1[/eqn]

and it should become obvious.

>>7683605
1+1 =2
12+11=23
1.01+1.02=2.03
etc.

I've got a hollow circular plate. It's got a spring (400 N) pressing down on it, and it's welded at the ends. I'm trying to calculate the moment - how do I interpret the force, can I just assume it's a point load?

All I've been taught is beams so I have no idea how determine the stresses from a "circle shaped" load.

>>7683557
"In mathematics, the mean value theorem states, roughly: that given a planar arc between two endpoints, there is at least one point at which the tangent to the arc is parallel to the secant through its endpoints."
Let's do this indirectly: suppose there exists b>0 such that e^b≤1+b. From the mean value theorem, there exists 0<c<b such that (e^c)'=(e^b-1)/b, since the tangent line has the same slope as the secant line at least for one value between 0 and b.
(e^c)' = e^c, so e^c = (e^b-1)/b. If e^b ≤ 1+b then (e^b-1)/b ≤ ((1+b)-1)/b = b/b = 1.
So if e^b≤1+b was true, then there existed c>0 such that e^c=1, however no such c exists (you can prove that by solving for c and using the properties of logarithms).

>>7683605
a lot of practice, patience, and more practice. I failed pre calculus 3 times before i took it online and had my brother passed it for me. i was too impatient at the time and did not practice.

can i get help flipping this y = to x = ? forget how to handle exponents

y = 4x^-1.5

>>7683646
pic related may help you understand it better.

How can the probability for picking a random number from the reals be 0 for any number? If I pick some number n, then the probability for n is 0, but it has just been picked, so it couldnt have been zero because then it wouldnt have been picked.

>>7683486
>>7683599

Me again. I don't seem to be able to solve this. I've tried different versions and I don't seem to get this one.

How do I integrate 45x^5sec^4(x^6)?
I tried doing integration by part using x^5 as u and dv as sec^4(x^6) because v will be tan^2x^6.
=(45x^5)(tan^2(x^6))-45int(tan^2(x^6))(5x^4)dx
and I'm stuck at this part because now I have a multiplication involving 2 different polynomials again.
What did I do wrong?

>>7683860
Quick, what's the derivative of X^6?

Is it good/bad to drink 200ml (6.7oz) of coconut milk every day?
It has a fat content of about 17% but they're MCFAs.

>>7683899
good probably. not all fat is bad. even cholesterol is good to eat despite what misguided memers tell you.

Limit of n/((primorial(n))^(1/n))?
Maple won't give me 5 decimals at n=10000000.

>>7682523
Lol is this CSUB?

if a photon travels at c in a vacuum then in it's rest frame the universe undergoes infinite length contraction as γ=1/0 so Lim v→c , γ→∞
if this is the case why does light travel at c and not infinitely fast, why does it still have a travel time if the distance it travels is infinitelt small → 0

>>7682735
Can anyone please tell me if this statement is valid or invalid?

stupid graph theory question, can there be a graph with chromatic number 3 and 2015 edges?

Is there anything wrong with trying to get admitted to a doctoral program with the intention of dropping out after 3-4 semesters? I think it would be a lot of fun to do about 3 more semesters of school and to be able to call myself a phd dropout. I've got strong grades in a reasonably rigorous program and some good letters from some profs I did research with as an undergrad so i think i could get someone to let me do it as well.

I am too retarded to prove, give me a hint /sci/

>>7684359
For a second I thought your post said "proofs" instead of "profs".

This board is getting to me.

>>7684121

Community College.

>>7684373
You're in a class about calc/analysis. A common trick you need to develop in these courses--especially rigorous ones where you're squeezing everything into inequalities--is to add and subtract a convenient middleman. Think of what would help each limit on their own, add and subtract this quantity (so that the net contribution is zero), then interpret what the negative quantities can be transformed into that looks more familiar.

>>7682386
How many heart beats does it take for a blood cell to make one round around your veins?

>>7684373
If f is differentiable, we have the estimations:
[eqn]f(x+h) = f(x) + hf'(x) + o(h)[/eqn]
[eqn]f(x-h) = f(x) - hf'(x) + o(h)[/eqn]
Therefore:
[eqn]\frac{f(x+h)-f(x-h)}{2h} = f'(x) + o(1)[/eqn]
which goes to f'(x) as h goes to 0.

>>7683645
always take springs as point loads.
take the reaction force to be a shear stress distribution acting on the welded face of your circular disk.

If you add all the digts in a number those it equal a multiple of that number?
like 792
7+9+2=18
792/18=44

>>7683626
>>7683646
Thanks both of you!

why do mathematicians say dirac is not a function? by which definition is it not one and what are the implications? meaning, what would be true if it was a function but is actually false?

>>7684759
that is only true for 9. 297 also has 18 as a digit sum but is not divided by 18.

you have probably done it.... but.
Let u=X^6 du=6x^5 ... then you go from there

>>7683874
6x^5?

>>7684063
Pleasse telle me aboutt this .

I know Markov Chains can be represented by a Matrix and a Markov Process by a Matrix-vector multiplication. Where do I go from here assuming I want to know everything about the application of Linear Algebra in Markov Chains?

A philosophy major said that high level science require philosopher to develop new theory.

He's retarted right?

>>7682386
If I want to be they guy that determines how many calories something has so they can put it on the package, what should I study?

Welding school dumbass here.
I just wanna know why the contraction of one particular piece of metal that's cooling is bigger than its dilation when receiving heat (ie why does welded metal ends up shrinking).

I tried googling it but to no avail.

>>7684550
Would the reactant force at the welds just be the same as the spring? I'm really unsure of going about this because of the round shape. Also when I calculate the shear stress, which cross sectional area do I need to use? Sorry for the stupid questions, I've been trying all day to understand the problem but the disc just throws me off.

>>7684829
I got it! Thanks!

In -n+2, why isn't the expression undefined if n=2?

>>7685535
What's that equal to mate? If it's just written like that, then it's undefined already.

Now for a question of my own, and thank god this is a stupid question thread because this is pretty damn stupid:

I'm trying to solve [math]|x|-\frac{3}{x}>2[/math]. I know the solutions are [math]x>3[/math] and [math]x<0[/math]. If [math]x>0[/math] then all is fine and dandy, and I get the first solution. However, when [math]x<0[/math] I run into a wall; here are the steps I have so far

[math]|x|-\frac{3}{x}>2[/math]
Multiply by x. Since [math]x<0[/math] then the inequality is reversed and
[math]|x|=-x[/math]
so
[math]-x^2-3<2x[/math]
[math]-x^2-2x-3<0[/math]
Multiply by [math]-1[/math]
[math]x^2+2x+3>0[/math]
And right there is where I get stuck. Any help?

is it possible to exchange my perscription medication?

i asked the pharmacy to give me a generic version of adderall xr to save me some money, and they gave me the actavis version.

i googled it when i got home and i've been reading nothing but bad things about it, and i'm starting to regret letting them give me this version.

maybe this is the vocal minority, because why would anyone who doesn't notice a difference feel the need to tell anyone about it, but if it's possible to exchange it i'd like to, just to be safe. I don't want to go a month without the productivity adderall gives me.

i haven't taken any yet, i won't until tomorrow morning, so i'm wondering if i can still return it?

>>7684759
>>7684759
No you can easily disprove this with prime numbers. Pick any two digit prime number and this will not be true.

Every time you write "Ax", as in the dot product between A matrix and x vector, the vector is technically 1x2, right?

Is this shit continuous at (0,0)?

What would be the limit of the function as (x,y) -> (0,0)?

If it is indeed continuous shouldn't the limit be zero? Is it true the limit at (0,0) doesn't exist because we get different values approaching along the x or y axis and using y=x^(1/2)? (0 and 1/2)

>>7685795
You said it just right, it's not continuous. Is there any reason it should be?

>>7685795
Based on the graph, yeah since the functions discontinuity was at (0,0,0) and f(x,y) is 0 when x and y are 0 (by definition)... and as to your limit question, 0.

>>7685561
All numbers = a solution.

Though I'm thinking of it more in terns of

|x| - (3/x) > 2
|x|(x) - (3/x)(x) > 2(x)
|x|(x) - 3 > 2x
|x|(x) - 3 - 2x > 2x - 2x
|x|(x) - 3 - 2x > 0
Calling it x^2, idk why
Except for the fact that all absolute values equal positive.
x^2 - 3 - 2x > 0
FOIL obviosly.
(x^2 - 2x - 3) > 0
FOIL
(x-3)(x+1) > 0

>>7685561
You never should've flipped the inequality?

>>7685819
>>7685561
>"The Exception: Negative Numbers. There is one very important exception to the rule that multiplying or dividing an inequality is the same as multiplying or dividing an equation. Whenever you multiply or divide an inequality by a negative number, you must flip the inequality sign."

YA.

>>7685818
-1's got to be excluded within that solution set though.

Unable to put it into proper notation.

>>7685836
i.e. All negative numbers that do not equal -1.

/sci/, I need to send my transcript from one CC to another CC. I need to do it to remove the pre-requisite to register for Physics. If I do this, and I transfer to a 4- year university do I have to send all transcript from every CC? If I do, will the 4-year university think that I did 60 credits in one CC and 60 credits from another CC? Or will they know that those are just transferred credits?

>>7685561
Well, if you consider f(x)=x^2+2x+3 you have a parabola without real roots (negative discriminant), so if a pair (x,y) belongs to the parabola the function always evaluates either to negative values or positive values. Since this one points upwards, it's the second case.

I'm not sure if you're required to, but you can argue this is true because a parabola is a continuous function in the real line. Then, you can use Bolzano's theorem, that says that if 'a' exists so that f(a)>0 and 'b' exists, so that f(b)<0, f a continous function from real numbers to real numbers, then 'c' exists so that f(c)=0. The opposite is also true, which means that if there's no c so that f(c)=0, then there can't exist both a and b that evaluate to both positive and negative numbers each.

>>7685810
If I plug the function [math]xy^2/(x^2+y^4)[/math] on WolframAlpha it says the limit for f(0,0) = 0.

So what am I missing here? Does it have to do with the square root of negative numbers somehow? I thought showing we get two different limits would prove the limit is path-dependent, and so it doesn't exist.

>>7685811
I believe for a function f to be continuous at (0,0) we must have:
[eqn]\lim_{(x,y) \to (0,0)} f(x,y) = f(0,0)[/eqn]
But if such limit doesn't exist then we can't 'make' the function continuous defining it just like that (f(0,0) = 0.)

I'm not sure, tho. That's why I want to know what I'm missing.

>>7685866
There's no way a function is continuous in a point if when you approach it with different curves you get a different result, by definition there can be only tend to one "limit" aproaching a point. In R2, that limit exists if and only if, aproaching by EVERY curve the function also aproaches said limit. That makes it impossible to prove a function is continuous by testing every curve, but it is enough to prove it isn't if you find one it diverges or tend to somwhere else. Which is what's happening.

Wolfram's algorithm is probably not that strong, it's a pretty tricky discontinuity after all. As you may know, if you watch the function through most curves it will actually tend to 0.

So... Yeah, trust me, it's not continous. I remember this exercise, it was the first "tricky" example I learned when studying continuity. If you're not convinced, just manually replace "y" with "sqrt(x)" and try Wolfram again.

>>7685864
Actually, wait, what?

Can somebody explain to me why multiplying by x is valid? I've been doing it too, but aren't you transforming a rational function into a parabola? The (x,y) solutions change a bunch, don't they?

>>7685889
Hahah, it might be that. I guess it just feels kinda odd that Wolfram fails. I'll prove its discontinuity later with epsilon-delta, just for some peace of mind.

Thanks!

>>7684966
Well the next step is to study the equilibrium measures, the possible convergence to equilibrium and the convergence rate.
If your state space is finite, this can be done using linear algebra.

>>7684818
It depends on what you call a function.
Technically it is a function, but maybe not in the way you imagine.
It is a functional defined on the space of smooth compactly supported functions (or "test" functions) from R to R, which assigns to a function its value at 0 (ie. [math]\delta(f) = f(0)[/math]). So it is a function going from the set [math]\mathcal{D}(\mathbb R)[/math] of test functions to [math]\mathbb R[/math].
What people usually mean by saying that it is not a function is that there is no "nice" function g from R to R (say locally integrable) such that [math]\delta[/math] coincides with the functional [math]f \mapsto \int_{\mathbb R} g(t) f(t) dt[/math].
The thing is that in distribution theory, you don't characterize a function by its values at each point (that may not make sense for some classes of "functions") but rather by its behaviour when integrated against test functions so in saying that the dirac delta is not a function, they are saying that as a functional on [math]\mathcal{D}(\mathbb R[/math], it does not behave like the functional defined by a "real" function from R to R.

What are the roots of Legendre polynomials to be used when interpolating?

>>7685955
Thank you, do you have any book/pdf recommendations on this?

>>7682735
It´s valid,if by ( , ) you mean the inner product on R^3. The cross product of two vectors is always orthogonal to both of the vectors hence also to any vector which is linear dependent to one of them, in this case w.

>>7683119
It says that I need a calculus background.... oh well, it is free at least.

I can see how it makes sense mathematically ( I saw the proof) but how does it make sense visually? It feel like visually you'd have to subtract the overlapping area between the circles?

Any tips on writing a good scientific paper? What do you normally include in the introduction,method? ect. This is for Physics btw

>>7686335
Also, a quetion about the proof:

I don't really get the transition from the 4th line to the 5th line .. How did they reduce that sum?

>>7686342
Wikipedia does something v similar in 2nd line to 3rd line, but I don't get it how it works... Someone pls help

>>7686335
>It feel like visually you'd have to subtract the overlapping area between the circles?
you do.
thats Y|X (=all elements that are in Y but NOT in X)

>>7686342
>>7686379

Note that y only appears in the joint probability function. Break the sum down into two dimensions: [math]\sum_x \left[ \log_2p(x) \left(\sum_y p(x,y) \right) \right][/math]. Sum of a joint probability function along a single dimension is marginal probability, so [math]p(x) = \sum_y p(x,y)[/math] by definition of joint probability function.

>>7686396
>thats Y|X (=all elements that are in Y but NOT in X)

Wait, is it? This is confusing, I thought I was just looking at the conditional entropy... What's with the dashed line then? Is it not part of the conditional entropy?

>>7686399
Damn, this does make sense, thanks. How come everyone skips that step? How come it is evident to everyone that's not me?

>>7686341
I'm in math, so I can only speak for the introduction (this might be different in physics, but I doubt it). You should do a literature review of the topic (this is perhaps the most important part) -- what are other people in the field doing? What have they said about this? How does your paper fit in? What is the reason behind doing the work in your paper, i.e. why is it a reasonable question to ask? You should go over the main result in simple terms so the reader knows what to look for, and give a roadmap of what can be found in each section.

>>7686410
Thanks mate that was helpful, the only problems is that this is a mock one for a 2nd year lab so I aren't doing any real groundbreaking research. I'm just investigating the speed of sound using resonance, a technique developed in the 1800's

>>>/v/318165917

/v/ needs your help.

>>7682386
I could not help but notice your png was not optimized anon.
I have optimized your png.
Your png is now optimized.

>>7686659

Looks the same.

From where do we get our mathematical axioms? Somewhere else than from thin air? Especially the more complex ones, not such simple as a+b=b+a

>>7686822
Axioms are givens of a system. They are accepted as being true and are used as starting points for logical inference.

>>7686822
Also commutativity is not an axiom.

What would be a good introduction to life in hydrocarbons? I tried to look around but I got nothing worthwhile.

Last step... can anyone please explain me where the sum on p(x) disappear?

>>7686975
Nvm i think i got it... the log is moved before the sum, and then the sum of probabilities is 1

>>7686975
You go to Warwick by any chance?

>>7686774
look at the file size.

How the fuck do you know how many significant figures during stoichiometry equations? Im getting answerz that are like 0.05 off from what my textbook says are the right answers

I know it has to do with rounding how the fuck do I know how far to round

Yes I know this is a retarded question

How hard is it to take a short-term(8 weeks) history class? I'm taking Chemistry 101, Physics I, Biology I (8 weeks), and Nutrition (8 weeks).

I'm 29 and don't know jack shit, and am pretty happy just wageslavin.

I've been listening to lectures on particle physics though and think it's cool af. My math knowledge goes about as far as basic dumbass algebra. Will my adult brain be too shitty at learning the advance math I'd need to really get into understanding this field? What's a good resource for learning math starting at this level (books, videos etc)?

Thanks

So I was doing some CAD homework and came across this 40 Degree angle and couldn't find a way to do it technically without the use of built in tangent restraints.

Anyways, how can I calculate the triangle for this circle so that I get this 40 degrees angle tangent to the upper circle and the base perpendicular to the bottom tangent.

>>7687512
To clarify lets say I only have the circle in white (R.50) to work with and have to draw the 40 degree angle.

>>7687525
To clarify lets say I only have the circle in white (R.50) to work with and have to draw the 40 degree angle.

>>7686659
Can this shit end?

KhanAcademy.org

And you should be able to handle courseloads just fine, so long as you DO NOT underestimate how much study time you will need to invest in this path.

>>7687512
>>7687525
>>7687528

I'm pretty sure I can help you out here but I don't 100% understand what you're asking... What exactly are you trying to accomplish?

>>7687546
This was for me, >>7687323 right?

I'm not trying to become a hardcore expert, I just want to understand more about what I'm learning and what's being discovered.

>>7687554
I am basically trying to calculate the dimensions of a triangle with a 40 degree angle that can fit perfectly a circle of a radius of .5.

It came to me how to do it, but I didn't do well in math.

I think that given I have all the angles here and it should be easy to calculate the dimensions given the angles, which if I am doing this correctly are 40, 90, and 50.

How can I detect anomalous data points? I want to reject data points that are highly implausible, with no delay (e.g. you can't know any data that comes after it). Like in pic related, I would have wanted to keep everything except for the one highlighted entry. I don't want to set a fixed threshold because if the aforementioned data point had been preceded by values such as (50, 60), (70, 70), (65, 65) then in that context it wouldn't have been anomalous.

guys this power series shit is pissing me off.

I have a seris n=0 to infinity of Asubn (x-2)^n

where it converges at x= -1 and diverges at x=6

im trying to figure out the smallest and largest intervals of convergence but I can't figure this shit out, its pissing me off. Any help would be appreciated on how to do this.

Seems I posted it in the wrong thread.


I'm supposed to find where F(x)= e^x*cosx is concave and where it is convex. The double derivative of that function is;
F''(x)= -2*e^x*sinx, and that gives at F''(x)<0 when on (2πK-π, 2πK) (K is a Natural Number) and F''(x)>0 when not.
Doesn't that mean that;
F(x) is convex when x is between (π-2πK, 2πK) and concave when not?

The answer the book gives is that it's convex on (-3π/4+2πK, π/4+2πK) and concave on (π/4+2πK, 5π/4+2πK).
Why?

>>7687592
>>7687592
Set it so that if the data point is more than say 30-40 off the previous to reject it?

>>7687626
Are you misreading the problem somehow? You did the double derivative right.

>>7687666
Yes F''(x) gives me -2e^x*(sinx) and I find where it's positive and/or negative. It's just that the answers the book prefers being different that really confuses me.

>>7687668
can someone pls explain me lagrange's way to find the maxima?

>>7688380
didn't mean to quote someone sorry

How do I prove that the integral between -infinity to infinity of (sin(ax)/x)^2 = a*pi, where a is a positive constant.

>>7688380
Let W, V be Banach spaces, let C be a non-empty, closed and convex subset of V, let K⊂V be a closed convex cone and J: W -> R and G: W -> V continuously Frechet differentiable functions.

Consider the optimation problem:

min_{w ∈ W} J(w)
subject to the constraints
G(w) ∈ K
w ∈ C
Then for every solution w of the optimation problem that also satisfies Robinson’s regularity condition we have a Lagrange multiplier q ∈ V* with

G(w) ∈ K
w ∈ C
q ∈ {l ∈ V* | l(v) <= 0 for all v in K}
q(G(w)) = 0
(J'(w) + G'(w)*q)(x-w) >= 0 for all x in C
The good thing about Lagrange's method is that you can just use generalized Newton methods to solve this system of constraints.

>>7688437
Well, thanks, but I guess by explaining I was thinking more like using easy to understand language... sort of give an intuition and when people usually use it. Sorry for the confusing question

>>7688401
What, converges?

How do I determine the semi major and semi minor axis of an ellipse given that I have a function of the form:
[math]qx^2+wxy+uy^2=n[/math]
This is in Cartesian axis system.
I know that in the semi-minor and semi-major axis is should have a form
[math]frac{a^2}{x^2}+frac{b^2}{y^2}=1[/math]
I just don't know how to get there

>>7688459
Oops, sorry
[math]\frac{a^2}{x^2}+\frac{b^2}{y^2}=1[/math]

>>7688380
you do da mutil dimensional derivative of both functions but put a constant on the boundary function then and set it equals and ur done!

>>7688450
You can simply consider the special case where W = C = R^2, V = R, K = {0}, J = f and G = g then it tells you that for every optimal solution of the optimation problem:


min f(x,y)
subject to the constraint
g(x,y) = 0


there exists a Lagrange multiplier q with
g(x,y) = 0
∇f(x,y) + q ∇g(x,y) = 0

Any hints on how to show that the only solutions are +-1? Should I be looking to show it algebraically or is an explanation needed instead? I'm fine with the contradiction part.

>>7688490
|g|^(1/2) = g^m
|g| = g^(2m)
1 = |g|^(2m-1)
|g| = 1
g = -1 or g = 1

>>7684063
Isn't this a fairly interesting graph, /sci/?
n divided by the nth root of the nth prime product.

A similar sequence with the factorial in place of the primorial will yield e.

>>7688499
to make sure you cover all your bases, also mention that
1 = |g|^(2m - 1)
is valid if
2m - 1 = 0
but that contradicts the fact that m is an integer

EE major, have to do my term project soon. The assignment is to make and develop operator control screen connected to PLC. I thought about changing it to making a wireless control system of transhipment machine based on microcontroller or maybe Arduino. First one will give quite useful knowledge only for someone who intend to work as PLC engineer. In contrary, I intend to do some research in electronics and embedded systems in future, so I assume second one would be more useful and interesting. What do you think, should I change it?

>>7688512
If you are in a group vote on it. If you are by yourself do the most interesting one since you'll put more effort into it and produce a better product. I'd ask if it okay first though

>>7688512
definitely clear it with your instructor. What i've noticed is that instructors are generally okay with you modifying the project a bit as long as the end result in impressive and you learned a lot during the project

>>7688499
>>7688508
Yeah, thanks a lot.

>>7688515
Yeah, I was thinking the same.
>>7688519
It's not just modifying, but clearly different theme. And it'll be a harder one, when first one should be simplier. I'm just kinda late and instructor can be cocky when showing time comes.

>>7688515
Yeah, I was thinking the same.
>>7688519
It's not just modifying, but clearly different theme. And it'll be a harder one, when first one should be simplier. I'm just kinda late and instructor can be cocky when showing time comes. He insists that I should do the first one.

>>7688401
Maybe use a contour integration, using functions like [math]f_{\epsilon}(x) = \frac{\sin^2(ax)}{x^2 + \epsilon^2}[/math].
These are integrable on R and I think you can compute the integral using the residue theorem. Then, if it works, you can use Beppo-Levi's theorem to prove that [math] \int f_{1/n} \mapsto \int f_0[/math]

Can I say that completeness implies that the distance between 2 consecutive elements of R is 0? Feels really wrong since I could then say that R = some number.

>>7688621
Define consecutive

>>7688651
Yeah, I thought it fell down there... If I said a and b were two consecutive elements, you could then show that there's an element between those... So, would it be true to say that 2R =/= R? (2R is a left coset of R)

>>7688660
Well no, you do have 2R = R (obviously 2R is a subset of R and if x is in R then x = 2(x/2) , therefore x is in 2R so R is a subset if 2R)

So, I'm having trouble with a Lebesgue integral.
[math]D=\{x∈ R^2 : x_{1},x_{2}>0, \sqrt{x_{1}}<x_{2}<2\sqrt{x_{1}}, \frac{1}{x_{1}}<x_{2}< \frac{2}{x_{1}}\}[/math]
[math]f(x)= \sqrt{x_{1}}x_{2}[/math]
[math]\int_{D}f(x)dx[/math]
I know I have to find a transformation for [math]x_{1}[/math] and [math]x_{2}[/math] and adjust the limits but I seem to be too stupid to do it.

>>7688756
Just transform it to the unit square.

>>7688773
I would if I could.

>>7688787
Your inequalities LITERALLY say
[math] 0 < \frac{x_2}{\sqrt{x_1}} - 1 < 1 [/math]
[math] 0 < x_1 x_2 - 1 < 1 [/math]

Just how mentally retarded does someone have to be to not see a unit square there?

>>7688806
try to be nice sometime man

>>7688733
Ah, gotcha. Honestly thought that at first but my reasoning >>7688621 was terribly wrong. Do you know any basic books on abstract algebra since I find this module pretty difficult?

>>7688806
Wow, now I do feel retarded. In my defense, that's the very first integral of that form I have to calculate and I was so focused on finding a proper transformation I didn't think about the inequalities. Thanks.

>>7682386
you fucking retard, you're supposed to make the subject SQT or at least include those letters, so people can find the thread quickly via
http://boards.4chan.org/sci/sqt

Anyway, how do i condition a child to become a Math prodigy? I don't have a child yet, but when i do, i want to raise him/her to become a prodigy. is that even possible or is it genetics?

Can some one explain to me in small and simple words why this gets factored by -1 ?

A masspoint moves on a line, parallel to the x-axis , if I apply force on it in the same direction (in x-axis direction), what is the angular momentum?
I am not sure if it 0 or not

Do you use rounded values for calculations or would you use the value from a calculator?

Why is it that when you're writing in academics, you have to summarize the research articles you're basing the direction of your research on, rather than just copying and pasting their abstract with proper citation? That seems like a much more efficient system.

Gee I don't know, I guess Artin is good but I don't know if it would be good for a beginner... I guess it wouldn't hurt if you tried it (my teachers were fairly thorough in my first years so I have not seriously worked with a book before my third year)

>>7688985
Ugh I was answering >>7688812

Firstly, I am an idiot. Secondly, isn't there a name for a number that is the midpoint of the range of a set of numbers? Like, in the set of numbers 66 70 71 73 75 78 78, the mean is the average, the median is 73, the mode is 78, the range is 12, but what is the number 72? Like, the mean of the range, between 66 and 78, the midpoint is 72. Is there a name for a number that is the mean of the lowest and highest numbers of a set? I feel like there is but I've forgotten it, some fifth number that isn't mean, median, mode or range.

>>7688922
That is such a vague question.

Where can I access science journal papers? I heard some torrent site dedicated to it got taken down recently(?). Was there an alternative?

>>7689007
booksc dot org

I'm trying to prove that on [math]V/_{\mathbb{C}}[/math], for the set of matrix(es?) with complex entries [math]\mathcal{M}_{n\times n}(\mathbb{C})[/math] the operator defined as [math]\braket{\mathbb{B}|\mathbb{B}}= tr(\mathbb{B}^*\mathbb{A}[/math] (where tr is the matrix trace and [math]^*[/math] is the conjugate transpose) is an inner product. I'm basing myself off this list of properties http://mathworld.wolfram.com/HermitianInnerProduct.html, but I'm stuck on the last one ([math]\braket{\mathbb{A}|\mathbb{A}}\geq 0[/math]). What does it mean for a matrix to be greater than zero? Is it that it contains more than zero elements?

>>7689090
Goddammit 4chan, why wouldn't you have the braket package?

Anyways, trying again:

I'm trying to prove that on [math]V/_{\mathbb{C}}[/math], for the set of matrix(es?) with complex entries [math]\mathcal{M}_{n\times n}(\mathbb{C})[/math] the operator defined as [math]<\mathbb{B}|\mathbb{B}>= tr(\mathbb{B}^*\mathbb{A}[/math] (where [math]tr[/math] is the matrix trace and [math]^*[/math] is the conjugate transpose) is an inner product. I'm basing myself off this list of properties http://mathworld.wolfram.com/HermitianInnerProduct.html, but I'm stuck on the last one ([math]<\mathbb{A}|\mathbb{A}>\geq 0[/math]). What does it mean for a matrix to be greater than zero? Is it that it contains more than zero elements?

Ugh, that [math]<\mathbb{B}|\mathbb{B}>= tr(\mathbb{B}^*\mathbb{A}[/math] is supposed to be [math]<\mathbb{B}|\mathbb{B}>= tr(\mathbb{B}^*\mathbb{A})[/math]

>>7684063
Can someone please evaluate whether this converges to a null or a positive value?

Hi guys, this is a REALLY stupid question.

I'm taking calculus 1 right now and I noticed throughout the course that we had questions where we had to apply formulas that we learned to real life scenarios (like a bird flying, a car accelerating, a boat sinking, etc.). We are always asked these kinds of questions after we learned of the formula or law.

My stupid question is: in real life, did the questions come before the formula?
In other words, was it the case that we had a ball roll down a hill, and a person was curious if he could mathematically determine the time it would take to stop moving -- thus coming up with the formula for it? Or is it the case that the application of a known formula to a problem was always the way to go about it -- similar to how we are learning about calculus?

Thanks.

>>7689653
I could not help but notice your gif was not optimized anon.
I have optimized your gif.
Your gif is now optimized.

Speaking of stupid questions, is Biology a science?

I have a 16 year old nephew who is soon to be 17. He's still in the 10th grade and he had two Fs in 9th grade. Well, 2 Fs in the first semester and two Fs in the second semester, but the same two classes; English and Math. Now, this is the first semester of 10th grade and he has four Fs. They are in the 30% range, and with only 2-3 weeks left of school, it's doubtful that he'll bring those grades up. The father is doing life in prison and the mother is a crazy one who cares more about how she looks and money rather than trying to help her kid. My grandparents can't do anything since the mother essentially enables him. I can't do anything because I have no real power since I'm just an uncle. He's the typical teenager who doesn't give a shit about school and would rather spend 10 hours a day playing video games. Is there anything we can do, or is it a loss cause? I have my suspicion that once he's 18, he's gonna drop out of high school and be a bum.

>>7689699
There is nothing you can do to change him, but you can influence his environment.

Take him out. Be a role model. It doesn't seem like he likes sports, so take him fishing. Or throw a frisbee with him. Teach him skills that he can use to his advantage, like meeting new people, and shaking people's hands. And building things. Take him to a maker faire/shop. There he can meet other people (such as STEM students). There, with the people he met, he can subconsciously pick their brain, and grow some motivation to do something different with his life.

If he doesn't like that shit, take him to a music concert. If he doesn't like music, change the genre. Try taking him to a contemporary dance concert. A ballet recital, even.

If he doesn't like any of that, take him to a car show/meet.

If he doesn't like any of the above, try building something with him. Like a deck or a doghouse if you have dog(s). I loved renovating the house and painting the walls with my dad.

>>7689653
Yes, of course, the questions came before the formula.
Being able to make satisfying quantitative predictions was the motivation for inventing these notions

>>7688846
it's possible. this kid might be autistic but his dad probably spent a lot of time helping him memorize stuff. teach the kid math and logic and such things instead of doing trivial shit like memorizing the periodic table. most people aren't legit retarded, they just suck at math because they didn't get taught properly.

https://www.youtube.com/watch?v=1E9vj4WmHLM

Can someone help me with b?

I found a, which is Sigma n=0 to infinity of ((-1)^n (x^n))/(n+1)

but for question b, I don't understand what he's asking me to do.

How do I get a series of that function? pls help im lost.

How do you calculate digits of pi by hand?
that is without computers and with math knowledge that was available when the first approximations were made and obviously knowing all the n-1 digits

>>7684063
How to evaluate the convergence of something like this?

>>7689655
What is that shape and what is its area?

>>7682386
any of you brainfags can recommend me a good book about x-ray crystallography

>>7690024
I would do this for the area
area of circle+
(area of single oval - area in common between oval and circle)*4
The bit in the parenthesis should give you the area of two of the top arc things, since there's 8 you multiply it by 4

>>7689096
>A Hermitian inner product on a complex vector space V is a complex-valued bilinear form on V
A bilinear form always maps from a vector space to the associated field, in your case from the vector space of complex matrices to [math]\mathbb{C}[/math]. Thats true for the map you defined, because the trace of a matrix complex number. So first of all <A,A> is not a matrix but a (complex) number. In fact its even a real number, which you can see by using the fact that your form is indee Hermitan (property 5 in your list). So if it´s a real number you can check if it´s always greter or equel than zero and zero if and only if A=0, meaning the zero-matrix.

How do I calculate the percentage chance?
Two objects are travelling towards eachother at 2150 Meters per second each.
Both objects are 5m long.
And there's a thing that happens thirty times per second.
What's the chance that the objects are overlapping when that thing happens?

>>7689653
No shit the former came first. We constantly wonder about FTL travel, but we don't have any way of modelling how to do it mathematically.

My lab manual for this physics lab gives us the equation [math]\frac{v_{1f}-v_{2f}}{v_{1i}-v_{2i}} = -1 [/math] for elastic collisions.

I'm struggling to figure out how they came up with this equation, knowing the formulas for conservation of momentum and kinetic energy for elastic collisions. Is it simple algebra?

The closest I've got is taking [math]\frac{1}{2}m_1v_{1i}^2 + \frac{1}{2}m_2v_{2i}^2 & = \frac{1}{2}m_1v_{1f}^2 + \frac{1}{2}m_2v_{2f}^2[/math] and replacing the [math]mv[/math]s with [math]p[/math]s, and canceling out the halves. This gives me [math]p_{1i}v_{1i} + p_{2i}v_{2i} & = p_{1f}v_{1f} + p_{2f}v_{2f}[/math]. However, I also know that [math]p_{1i} + p_{2i} & = p_{1f} + p_{2f}[/math]. Are those last two equations enough to figure out that first equation, or is there a step I'm missing?

I really hope I didn't fuck up my LaTeX.

>>7690743
I fucked up my latex

How do I prove that sin(1/x) is integrable on [0,1]?
If I try to show that the lower and upper sums are equal to show that the function is integrable then I get an infinite sum with a trig function which I cant compute. Anyone have any ideas?

Hi /sci/ I feel like a dumbass today cuz I didn't understand a simple proof in linear algebra and was wondering if you could help me.

x is the Eigenvector for A with Eigenvalue lambda and y is the Eigenvector for A transpose with Eigen value mu. If lambda not equal to mu then x*y=0.

Im not sure why I cant this but I was hoping something would click. Im guessing I need to show elements of null spaces are orthogonal so that x*y=0. However im not sure how to show nullspaces are orthogonal just based on the fact that lambda not equal to mu

thanks

If I have an object suspended in a liquid, say water, and a force is applied to it so that it oscillates, would the Density of the water be considered the Damping Factor?

What does it mean when a girl taps my shoulder, I get startled, and the group around laugh. Afterwards, as she is talking to me, everyone is just staring at our conversation? This happened on Friday where the professor didn't show up because she was stuck in traffic. She just wanted to tell me that she called the professor and that she wasn't going to show up.

My English professor came up to me after class and told me to send her two of my previous essays because they were really good and wanted to show the class how to write an effective essay. Is this a trap? I completely suck at English, so this came as a surprise to me. You think that she just wanted to check if I cheated by inserting them on blackboard's safe-assign?

>>7690584
Try to think of it as a 5m thick wall and a 5m bar traveling at double the speed.
thing happens every 71.6 meters
i'd say it's the same % as 5 over 71.6.
7% if i'm not mistaken

>>7691090
prove that it is differentiable?

>>7691705
>english professor compliments me and ask for more of my work
>must be a trap
nah, i assure you if you read something shit you don't ask the author for more shit.
send em unless you copied a LOT of the essays from some other source

>>7690750
both momenta can't be positive, otherwise the objects that are supposed to collide are going in the same direction.

someone want to prove this sequence is bounded for me?

[math]a_{0} = 1, a_{n} = \sqrt{4+a_{n-1}}[/math] for all [math]n \geq 1[/math]

i'm too tired to finish it..

If I understood this correctly, a finite set paired with any binary operation CANNOT ever be a group since it will never have closure?

>>7692008
*additive operation

>>7691778
I'll take that as me doing the calculation correctly the first time.
Thanks for the confirmation bud.

>>7691948
Every element is less than 10.
a_0 = 1 < 10
and if a_{n-1} < 10 then
a_n = \sqrt{4 + a_{n-1}} < \sqrt{4 + 10} < 10

Repeating Linear Algebra because I'm a dumb fuck.

Vector space V is defined as the span of <1, x, sin x, cos x>. Let W be the subspace of V, where all functions satisfy f(pi) = 0. Find the basis of W.

>>7692175
First find a linear transformation that maps V to W.
The column of the matrix of that transformation span W.
Remove linear dependent vectors from the span until you have a basis of W.

>>7682386
how can i show that the limit for lim n-> infinite a^n = 0 for 0<a<1 ?
It's a task with 5 points so it should be rather detailed,

>>7692440

Could anyone tell me how do I tackle this? "Prove that for every positive rational number y, exists a rational number x where exp(x) = y "

>>7692515
You can't prove it because it's wrong.

>>7692515
>>7692525
Sorry, I made a mistake, "Prove that for every positive real number y, exists a real number x where exp(x) = y "

>>7692440
anyone please?
I have to prove that
[math]
\lim\limits_{n \rightarrow \infty}{a^{n}}=0
[/math] for [math] 0<a<1 [/math]

I have to show that [math]\Diamond \Diamond \varphi \rightarrow \Diamond \Diamond \Diamond \Diamond \Diamond \varphi[/math] is not derivable under Kripke logic.

Obviously this implication isn't true since it's simple to construct a model in which this isn't true (a linear model with three worlds that satisfies the precedent for the first world) but showing that it isn't derivable seems to be considerably harder.

With that I mean that there doesn't seem to be an obvious way to construct a contradiction from this statement. I don't need a solution, just a pointer as currently I'm getting stuck since there aren't many derivative truths I can derive from this that I can use to advance.

Should I get a Physics I professor who has a 3.9 overall rating at ratemyprofessor with a 4.0 in Helpfullness and Clarity while a 1.9 in easyness or should I get a professor who has an overall rating of 2.5 with a 2.5 rating in Helpfulness and Clarity with a 1.7 in easyness. The 2.5 professor is 20 minutes away while the 3.9 professor is 60 minutes away. I have never taken Physics before and I am not really smart, so it takes a good professor to teach me.

Is the majority of mammals on this planet herbivores or carnivores?

>>7692673
There are only omnivores.

>>7692534
Show that it is continuous and unbounded above, and that [math]\lim_{x\to-\infty} \exp(x) = 0[/math]

>>7692681
Let me rephrase that then.
Do the majority of mammals survive mainly on a meat based diet or on a plant based diet?

>>7692673

Humans are the most numerous mammal and are omnivores.

>>7692686
Gosh darnit.
I mean different species of mammals.

I've got some Gallium and I want to make it reactive to magnets. Either attracted or repelled. What can I do to achieve this?

>>7685626
p= 07

:^)

>>7692869
need answers

>>7691090
[eqn]\int_{\varepsilon}^1 \sin\left(\frac{1}{x}\right) = \int_{1}^{1/ \varepsilon} \frac{\sin u}{u^2} du[/eqn]

I suck at this

{0,1,...,12}
1013023 + 3141009 ≡ __ mod 13

what do they actually want from me
we always just did something like 28 ≡ 3 mod 5 and check if it's true

Stats/ML:

Say you have a dataset. Couple thousand data points each with about 40 real variables, and a real number as output for each data point.

How do you process data? Like I've read that I should use some descriptive stats and get the mean/variance for each variable, check if the variable distribution is skewed, plot the histogram for each data point... but what for? What am I to do with the mean? I know that I should try to get rid of some of the variables.. but how? I was thinking about generating some correlation matrix or doing some principal components analysis, but what else is there?

Basically how do you approach a regression problem like this (with no missing values btw)

Also, the dataset is the parkinson/voice measurements one if others are familiar with this

I want to sterilize large swaths of a certain population. I don't know enough about science to do it.
I was thinking about giving them free water with whatever chemical in it, I don't know what that chemical would be though.

What would it be, /sci/?


Pic related. Water is cheap.

>>7693085
They want you to give what 1013023 + 3141009 is congruent to mod 13. I.e. they want you to give the remainder of (1013023 + 3141009) / 13.

Congruence is pretty simple:
all answers are in the set 0 to 12.
12 + 1 = 13, 13 is congruent to 0 mod 13
14 is congruent to 1
15 is congruent to 2
etc. it just keeps cycling

a is congruent to b mod c (written a ≡ b mod c) if there exists an integer n such that a + c*n = b

For example
1013023 + 3141009 = 4154032
= 319540 * 13 + 12
So 4154032 ≡ 12 mod 13

How did I get 319540? Simple, I plugged 4154032/13 into a calculator and got lopped off the decimal. Then to get 12, I did 4154032 - 319540*13

In some cases (such as with multiplication) there will be more clever ways to calculate congruence based on the fundamental laws of modulus which you will probably learn if you haven't already.

>>7682386

I'M MOVING ON UP

>>7693668
good luck

>>7693668

Weird. When a waitlist is over 30, the college would open up another class.

Series a(n) has 2 partial limits. Series b(n) has 3 of them. Can the series a(n)+b(n) converge?
I think not because I couldn't find an example, but I don't know where to start the proof

>>7692869
Still need a simple answer to this

Shouldn't the answer be 1:3:5. What's happening?

>>7693859
plz

>>7693429
pls help

Geometry question here:
If i have a plane which has the form:
[math]\begin{pmatrix}5\\-1\\2\end{pmatrix} * x=3 with x \in \mathbb{R}^3[/math]
Then is there any way to get the 3 point form out of this or to plot it somehow?
The 3 is the inner product out of the two vectors you would additionally have.
Thanks in advance.

>>7694052
Here's the equation as a picture.

Does this question make sense?
>Find the probabilitiy that n people(n<=365) selected at random will have n different birthdays?
If it's the birthday problem then the question should read: Find the probability that n people selected at random will have different birthdays.
While this question says n different birthdays.
PIC related is the birthday problem formula.

>updating my C.V.
>President of a club starting in Spring 2014
>finishing my last semester currently
Should I list the timeframe on my C.V. as

>Spring 2014 - Fall 2015
or
>Spring 2014 - Spring 2016

I'm just curious to know if "Fall 2015" would imply that I am in my position through the entirety of the term, or if I stopped holding the position at the beginning of the term.

>>7694503
>- present

Hey guys... I've been trying to calculate this limit
Lim sqrt(y-x^2)
(x,y)->(1,5)
It's pretty obvious the answer's 2, but when I try to solve it using directions I fail, and I don't know why.

>>7689655
What do you use to optimize gifs, and is the process lossless? I know of optipng for pngs (lossless obviously) and jpegrescan for jpegs (doesn't create additional loss, tested it myself).

My math professor didn't know what a doi is. Should I change universities?

>>7689655
>>7695081
What does the optimization process do, and how come the image editors don't do it by default?

>>7695195
It does obvious things like recognizing grayscale images and changing the image type to grayscale from, say, truecolor (so less bits per pixel).
From the optipng site (http://optipng.sourceforge.net/pngtech/optipng.html):
>In the first stage, the image pixels are passed through a lossless arithmetic transformation named delta filtering. Filtering does not compress or otherwise reduce the size of the data, but it makes the data more compressible.
>In the second stage, the filtered byte sequence is passed through the Ziv-Lempel algorithm (LZ77), producing LZ77 codes that are further compressed by the Huffman algorithm in the third and final stage. The combination of the last two stages is referred to as the Deflate compression, a widely-used, patent-free algorithm for universal, lossless data compression. The maximum size of the LZ77 sliding window in Deflate is 32768 bytes, and the LZ77 matches can be between 3 and 258 bytes long.
>The role of filtering can be illustrated in the following example. Assume the sequence 2, 3, 4, 5, 6, 7, 8, 9. Although it has much redundancy, the sequence is not compressible by a Ziv-Lempel compressor, nor by a Huffman compressor. However, if one makes a simple and reversible transformation, replacing each value with the numerical difference between it and the value to its left, the sequence becomes 2, 1, 1, 1, 1, 1, 1, 1, which is highly compressible.
>The PNG format employs five types of filters: None, Left, Up, Average, and Paeth.
>A certain filter is assigned to each row, and is applied to all pixels from that row. Therefore, an image can be delta-filtered in a huge number of possible configurations (5^height), and each configuration leads to a different compressed output.
>While an exhaustive search is unfeasible, the PNG Specification suggests a heuristic filtering strategy: <heuristics here>
>[There exist] Cases where the above heuristics are less than optimal.

>>7695249
>It does obvious things *first* like recognizing grayscale images
Anyway, cont. The point is you can encode a png in a gorillion different ways and there is no way you could brute-force all of them, so you have to use heuristics to decide which way to encode. These heuristics often produce results that are far from best, so you have to try another, and another, and so on. The problem is that the more you try the longer it takes, so ofc most image editors don't do this.

Does anyone know a good book about basic electronics?

>>7684359
seems like a stupid waste of time

you'll only live for around 60-80 years. do you want to spend 2 years on this?

Why had Academic Critical Thinking courses abandoned Epistemology, Logical Fallacies and Cognitive Biases?

I've got the H NMR for this as well but, so far I know this structure has a primary amine, a C-H stretch (lol) and a possible ring according to its NMR. Does anyone have a clue or idea what it may be?

Please help /sci/

>be me
>27 years old
>want to become computer engineer
>enroll into a c++ programming course because it's needed for my major
>test #2
>have to program two problems
>unable to do it
>turn it in not like how the problem asked for

Should I just find something else to do? I wanted to become a computer engineer, and no other non-engineer is worth it, so what should I do?

>>7696039
You have to try harder. Programming is the one skill that you can apply almost everywhere.

My own question: Which board should I bother with my concept of a global economy that is a slight variation of capitalism?
Is this a question for /sci/? Or should I go over to /biz/?

>>7696084

You mean macroeconomics? /biz/ either way.

>>7696084
>You have to try harder. Programming is the one skill that you can apply almost everywhere.

I need to. What sucks is that I have Math, English, Oral communication, and an hour drive to the class that takes up so much time. If I didn't have Math and English, I could be programming 6+ hours everyday.

how can i describe this curve?

>>7696102
move closer to school. if you go to class 4 days a week, youre losing over 100 hours each semester that you can spend studying or dying something productive.

>>7696104

That looks like the top part of ellipse. Just take the formula for an ellipse and restrict the range.

Didn't get an answer last time. Why do higher frequencies of light diffract at shallower angles but refract at more extreme angles?

>>7696172
because refract is the opposite of diffract.
Duh.... physics much?

>>7696169
*domain.

>>7694263
Probably late but what ever.
The problem is asking what's the probability that for example 30 people have 30 different birthdays.
aka what's the possibility that n people have all different birthdays

Are there applications of the Van der Pol equation outside of biology?

>>7689871
>BTW
jesus thats horrific

>>7689871
If you know a theorem for integrating a function series (which requires uniform convergence), then use it to express the integral as a series.

How do I work division in chemical equations?
Does it work the same like addition eg. I just divide the products and reactants?

For example:

R- : Mg+X

>>7696339
>How do I work division in chemical equations?
with a very steady hand

>>7696222

Care to elaborate why they're opposite?

>>7696341

>>7696222
I think the opposite of diffract is focus
The opposite of refract is something that lets the thing go for his path unaffected.
transparency? non-tangibility? something of that effect

How many Kinder Eggs could I stick up my anus until I reach my small intestine?

>>7682661

How do I do feature selection based on descriptive statistics? I guess there's the correlation matrix, but what other stuff? People say they use mean and std but I don't understand how

>>7682661
sort of like don't waste time complaining or making excuses

>>7696420
Am I on the right track? I'm pretty sure the electrons on the H2O oxygen attack the epoxides at the least hindered position and add alcohols? I'm just having trouble forming that last ring on the left

>>7696417
what do you functionally want to do? which part of statistics you use to prove/corrolate something heavily depends on the nature of the subject(s) used.

>>7689488
Positive/Infinitely

Im using Newton's Method to find the roots of ln(x+1)+1. But what happens if the starting point yields a tangent with an Xintercept value which can't be used for further iterations?

>pic related. red line is the tangent

>>7694052
>>7694056
Anyone?
Here's another thought, if i would find a parallel line would i be able to get the other 3 point form?

>>7697018
It's intramolecular. The secondary alcohol attacks the first epoxide through a six membered TS, then the resultant alcohol attacks the second one similarly

>work very hard on paper draft
>advisor has a look
>says there's enough material for two papers and I should split it
>"I know you're a perfectionist Anon but it's better to stick to the basics, remove the more advanced part and submit it again in six or twelve months as new work based off the previous paper"

Is he right?

I just wanted to write a great paper.

>>7698345
Then the algorithm doesn't converge to a solution.

Look up contraction mappings, fixed point theorems and successive approximations.

>>7698345
You can view Newton's method as a fixed point method, and then perform stability analysis. Basically, the method is guaranteed to converge for a well behaved function if a certain condition holds on the derivative at the starting point.

>>7698445
Your advisor knows how things work. It's probably going to benefit your career to have two separate papers, even though that's fucking stupid.

someone pls help me >>7698522

I need some serious advice from people who have been through gradschool.


Basically I'm an MSc student and I'm fairly certain my professor (and adviser) undermarked my exam on my coursework finals; one I really needed to be a competitive candidate to get into the gradschool I wanted for my PhD, my thesis mark probably make up the difference.

He did the same shit to me in undergrad, said something about not wanting other people to suspect favourtism and I went from having the third highest grade in the class to pretty much dead average despite being fairly certain I did well on the exam (I didn't check up on it at the time because I didn't care that much about my undergrad grades that much with gradschool already lined up).

With this exam I'm pretty certain I was undermarked by about 20% based on what I estimated my minimum mark to be checking answers afterwards. It's possible that he suddenly decided to drastically increase the rigour of his marking style, but the other top students I talked to afterwards made obvious mistakes on major questions and after checking prescribed papers and textbooks I was right on all of them we discussed. Everyone else in the class basically had no idea what was going, I saw some of their scripts afterwards and their answers are horrific.


Should I try to bring it up with him (in a subtle way at least)? I know it's extremely difficult to change finals marks at this university, but it's possible. He always talks very highly of me to his academic and industry contacts and I would get a great letter of rec. from him. He doesn't know I'm trying to apply to top-schools. He has fairly specific research groups in mind at other institutions (where his collaborators are) where he wants me to do a PhD so he probably thinks I don't care about my grades because he can get me in there on my research alone regardless of my gpa.


I feel like both not doing anything and doing something is going to ruin my career. Halp.

>>7698445
It's a pretty fucked up practice done by mediocre research departments and the Chinese.

Good researchers won't bother because they don't need to publish 100 shitty papers when they get a many high impact ones.

Most people in the latter group will look down on you because it's obvious when you could've published it in a single paper.

It's your choice and it is very much a moral one. I can't tell you what to do only that I would not let anyone convince me to split two papers just so he/she can get an extra co-authorship.

Should I finish my A.S. in computer programming and analysis or get my A.A and transfer despite having no money for Uni?

What do you write about when the experiment goes wrong? Was trying to find the cubic structure of a salt but it came out as inconclusive, should have been FCC

>>7698997
You don't really need more than associates for a programming career, most people get about the same salaries as BSc holding programmers anyway.

any idea why my priority queue messes up when there's more than 1 item with a priority of 1?

struct PQCell
{
PQItemType item;
PQPriorityType priority;
PQCell* next;
};

// Function insert inserts a new item x with priority p into priority queue q.
void insert(PriorityQueue& q, const PQItemType& x, PQPriorityType p)
{
PQCell* newCell = new PQCell;
newCell->item = x;
newCell->priority = p;
if(isEmpty(q) || (p<q.ptr->priority))
{
newCell->next = q.ptr;
q.ptr = newCell;
}
else
{
PQCell* leaderCell = q.ptr;
PQCell* followerCell = NULL;
while(leaderCell != NULL && p > leaderCell->priority)
{
followerCell = leaderCell;
leaderCell = leaderCell->next;
}
newCell->next = leaderCell;
if(followerCell != NULL)
{
followerCell->next=newCell;
}
}
}

// Function remove removes the item with the smallest priority from priority queue q.
// It stores the removed item into x, and its priority into p.
// If q is empty, remove does nothing.
void remove(PriorityQueue& q, PQItemType& x, PQPriorityType& p)
{
if(!(isEmpty(q)))
{
x = q.ptr->item;
p = q.ptr->priority;
PQCell* tempPtr = q.ptr;
q.ptr = tempPtr->next;
delete tempPtr;
}
}

// Function printPriorityQueue prints the contents of priority queue q in order from lowest priority to highest to the standard input.
// Prints the priority first, then a tab, then the item, then a newline character.
// If q is empty, the function does nothing.
void printPriorityQueue(const PriorityQueue& q, ItemPrinter pi, PriorityPrinter pp)
{
PQCell* scanCell = q.ptr;
while(scanCell != NULL)
{
pp(scanCell->priority);
printf(" ");
pi(scanCell->item);
printf("\n");
scanCell = scanCell->next;
}
}


>>7699004
>What do you write about when the experiment goes wrong?
You should spend the majority of the paper writing down about all the difficulties and possibilities that could've fucked up your experiment and emphasize what needs to be changed/added in future work to do it right.

>>7699027
>majority of the paper
Of the discussion and conclusion section I mean.

UCF a good school for potential CS/CE majors? The the high pop. and crime I hear kinda put me off...

>>7699030
>>7699027
Cheers man, I have done that, I think I know the main errors, contaminants and air pockets being the main ones. Hopefully I don't get an autist marking it expecting all experiments to go perfectly

Can anyone confirm that I've got these types of reactions right?

1- Double displacement
2- Neutralization
3- Synthesis
4- Substitution
5- Substitution
6- Decomposition

I know nothing about this, basically I just Googled.

>>7699247
Physics fag here so I can't remember too much of my high school chem. 6 is deffo (thermal) decomp, 2 is deffo neutralization

>>7692592
Since 0 < a < 1, you'll see that the bigger the exponent gets, the result will gradually get smaller and approach 0.

That's why [math]lim_{\n \to \infty} a^{n}=0[/math] for [math]0<a<1[/math]

Both sides would be balanced if water wasn't there. Automatic balancer says it's impossible to balance because it's several reactions in one. Is removing the water the right way to balance it? Can I do that without breaking some rule?

>>7692440
I can't LaTeX but here's an idea
1) show the sequence has a limit - a bounded, monotinically decreasing function has to have a limit.

proving it's bounded is easy (take a^1 as a bound, show that a^n<a^1) and proving it's monotonically decreasing is easy too (show that a^(n+1) < a^n). both of these can be proved by simple algebra or by induction

2) let the limit equal L. the limit of a(n) and a(n+1) should be the same (rigorously, define a subsequence b(n) = a(n+1), every subsequence of a convergent sequence has to have the same limit as the sequence itself)

lim n->inf a^n = L
lim n->inf a^(n+1) = L
lim n->inf a*a^n = L
a*L = L
L = 0 Q.E.D.

this is the general method of proving convergence of sequences defined by recurrence relations, you should familiarize yourself with it

>>7699004
Consult the lab people in their office hours if you have the time, but generally >>7699027

>>7694052
>>7694056
if by a 3-point form you mean defining it parametrically with (x,y,z)=A+tB+vC where A.B.C are vectors, then A is the coordinate vector of a point on the plane and B and C are two vectors that span it (= that are parallel to it). Find 3 points arbitrarily, 1,2 and 3. Set the first one to be your "A", find B and C can be any random subtraction between the coordinates of 2 points you found.

sup /sci/
I'm a math major college freshman at a California community college. What's a good college/university for math majors to go into? I'm thinking of getting a graduate degree on pure math or CS theory.

Thinking of pic related but I don't think my chances are great coming from cc.

Hey, stupid calc 3 question

I know I can't use elementary operations to find the integral of sin(x^2), but I've got a problem telling me to find the double integral. More precisely;

Integral from 0 to 1 of (Integral from x to 1 of (sin(y^2) dy dx))

Do I mess with the bounds or something to get rid of that shit?

>>7699722
[eqn]\int_0^1 \int_x^1 \sin(y^2) dy dx = \int_0^1 \int_0^y \sin(y^2) dx dy = \int_0^1 y \sin(y^2) dy = \frac{1 - \cos 1}{2}[/eqn]

>>7699736
Oh nice. Why are you allowed to change the x to 1 into a y to 0 though? I feel like there's a fundamental point I'm missing.

>>7699740
The thing is that both integrals are equal to the integral of the function [math](x,y) \mapsto \sin(y^2)[/math] over the triangle [math]T = \{(x,y) \in \mathbb R^2 | 0 \le x \le y \le 1\}[/math]
To do that, you can first integrate with respect to y, then with respect to x (that's what you are asked to compute), but you can also integrate with respect to x, then to y (that is what I wrote). It is a consequence of Fubini's theorem that these two things are equal.

>>7699766
Oh, I get it. I should have actually tried looking at the area.

How do i solve.

[eqn]\frac{3}{20000}\int_{0}^{10}\int_{0}^{10}(x+y)*(x^2y^2) dx dy[/eqn]

>>7699594
I got a fucking 2400 and got rejected from that place. Good luck.

>>7682682
https://www.youtube.com/watch?v=Z8M2BTscoD4

This video explains exactly what you are asking.

How do I prove that (F [A])*=F*[A*] where A is an operator (and therefore F [A] a generic function of the operator)?

* is the usual complex conjugation

New thread: >>7700901