/sci/ - Science & Math

Is 128 IQ measured by the WAIS-III a good enough score to be considered intelligent or is it still in the midwit zone?
Also, are WAIS-III scores lower in general compared to other test methods?

>>16016265
IQ is a negative measure, not a positive one.
By that I mean, it was invented to diagnose mental retardation, not find geniuses.
So, while there is a general correlation between higher scores and better outcomes, it isn't amazingly strong or predictive.
Also, the verbal portion of the WAIS is debatably less predictive as well.
All in all, don't worry about it. 128 is good. If you take it again, you'll probably score differently.

Let R be a not necessarily commutative ring with unity. Is there an example of a simple R-module whose underlying abelian group is not simple?

>>16015839
How to get an academic gf without being an academic but retarded, unemployed and being socially inept?

>>16016339
I forgot to add I'm most interested in the case when both R and the module are finite.

>>16016355
You don't.

>>16016265
>is it still in the midwit zone?
128 is just shy of two standard deviations from the mean. You are not quite in the 97th percentile. Are you intelligent? Sure, compared to the mean. But three out of a hundred in the general population will be smarter than you. This general population doesn't mean a college classroom or the 4chan userbase or whatever, and it includes literal retards. Sounds like midwit to me.

>>16016620
So, how much of a bad idea is to continue my undergrad studies in mathematics given that I'm a midwit?

>>16016630
Well that's certainly a stupid question. No one who is successful at a career path has first taken an iq test to see if it was a good idea or not. They just do what they want to or enjoy.

Pure happiness, such as is felt while being held like a baby, reminds us of our life in the womb. Life in the womb was pure bliss. Pure being. Only object, no subject. No thoughts. No memory.

Despite no explicit memory, we retain a vague implicit feeling of this lived bliss. It calls to us, like a warm blanket. Is it what we call God? Is it God?

I must be missing some understanding of rs232 waveforms cuz I cant figure out what this is supposed to be,
>space = 0 = 3-15v
>mark = 1 = -3 - -15v
>idle = 1's
>start = 0
>7 bits LSB-MSB
>parity
>doesn't idle between characters

>>16016355
>How to get an academic gf without being an academic but retarded, unemployed and being socially inept?
How to get filthy rich without any complex thought? You don't. >>16016355

I am trying to prove a recurrence relation is big O using the substitution method, and proving it by induction.

[math]Suppose \ \ T(k) \leq c \cdot k\log k, \forall x < n. T(n) = 2T(n/2) + b [/math]

Then during these steps, it its like this
Inductive Step:
T(n) = 2T(n/2)+b
<= cnlogn + b
=...
<=...
=... (this step is only justified when n>= 5)
<= cnlogn

Is this allowed? And if so, do i have to make my base case greater than 5?

My difficulty is i am saying for all k less than n, but then in my proof i say this only works when n>=5.

>>16017472
The base case for induction can be any integer whatsoever. The proof is then valid for [math]n \ge[/math] the value you select.

How do you prove b? I've tried proving it directly using exact sequences but it just ends up being circular reasoning

Is a shrimp a small lobster or is a lobster a big shrimp?

>>16017480
I'm a bit confused as to why this is allowed. I'm reading it as

"Suppose the LHS is less or equal to the RHS with respect to k, for all values of k less than n."

But then in proving this is actually true, I am saying "This step is valid only when n is greater than some value."

Then i conclude "for all k less than n, the LHS is less or equal to the RHS, but only when n>=5"

So that means k < 5 during my proof, which means the step where i say "this step is valid only for n >=5" is actually false?

isnt this cheating?

>>16017967
If you want to prove that it holds for cases where n is less than 5, you can do those separately from your inductive proof. Nothing wrong with that.
You see that sort of thing a lot when working with primes, where the obvious way to proceed with induction only works if the prime is odd, so you have to handle the case of 2 separately

>>16017967
It's absolutely possible that induction will not work below some particular 'n'. The statement may not be valid for all values or requires a different proof.

For example [math]n! > n^2[/math] can be proved using induction but the typical base cases of n=0 or n=1 does not work since the equation is only true for n > 3.

>>16017480
This is not correct, because the induction hypothesis is contravariant. Thus, if the predicate is not monotonous, you induction principle is inconsistent. Induction over integers can be stated as

∀ (P ⊆ ℕ). 0 ∈ P (∀ n, n ∈ P (n + 1) ∈ P) ∀ n ∈ ℕ. n ∈ P

so to get it from some base integer n0, you have to set P := {n ∈ Q | n0 ≤ n} for some predicate Q.

>>16018000
huh? explain like I'm not a math grad.

>>16018000
>>16017472
>>16017967
does that mean i can't do this?

I thought the derivative of x would be [math]\frac{-hc}{\lambda k_{B} T}[/math], where the hell does this [math]\frac{-x}{\lambda_{max}}[/math] shit come from?

>>16018177
Did you forget the image?

>>16018338
>>16018177
Yes.

>>16018177
>>16018341
[eqn]\frac{d}{d \lambda} \left(\frac{hc}{\lambda k_B T}\right) = -\frac{hc}{\lambda^2 k_B T} = \frac{x}{\lambda}[/eqn]

>>16018177
>>16018341
[eqn]\frac{d}{d \lambda} \left(\frac{hc}{\lambda k_B T}\right) = -\frac{hc}{\lambda^2 k_B T} = \frac{-x}{\lambda}[/eqn]

>>16018348
Alright, now I see where you're coming from. Thank you.

I'm trying to understand products and quotients of vector spaces.
The product is defined as [math]U \times V = \{ (u, v) | u \in U,\, v \in V \}[/math]. The quotient seems to be a completely different object.

My stupid question is: why is it not defined as the inverse of the product?
Is there any operation that allows me to retrieve [math]V[/math] and [math]U[/math] from [math]U \times V[/math]?

>>16018348
>>16018341
I manipulated the equation to [eqn]
\frac{\lambda^6 \left( e^x - 1 \right)^2}{-\left(x + 5 \right)e^x + 5} = {8 \pi h c}
[/eqn]
But am unsure where to go from there.

>>16018373
Yeah, it's the canonical projections from the first and second coordinates, respectively.
Quotient spaces are basically taking a subspace and reducing it to a zero dimensional one (i.e., a point).

>>16015839
Can you solve any of these, step by step, so I can better understand how it's done?
Thanks in advance

>>16018448
Take the logarithm (using any base of your choosing) of each side of the equation in each of them to bring down the exponent.

>>16018373
You can already go from [math]U\times V[/math] to, say, [math]U[/math] by the projection map [math](u,v)\mapsto u[/math].
You're right that the quotient of two vector spaces is, in some sense, different from (direct) sums and products, because while [math]\text{dim}(U\oplus V)=\text{dim}(U)+\text{dim}(V)[/math] and [math]\text{dim}(U\times V)=\text{dim}(U)\text{dim}(V)[/math], for the quotient you instead have [math]\text{dim}(V/U)=\text{dim}(V)-\text{dim}(U)[/math].
This makes at least some sense, too, because much like how [math]\frac{x^n}{x^m}=x^{n-m}[/math], you have that [math]\text{dim}(\mathbb{R}^n/\mathbb{R}^m)=\text{dim}(\mathbb{R}^{n-m})[/math].

>>16018452
>Can you solve any of these, step by step

>>16015839
>failed f=ma today
how to get into usapho

i did all the past tests for practice and took physics C still no work

>>16018499
I told him the first step for each of the equations. After that he will have a simple equation for x.

>>16015839
Bad idea to go for a math major? Am I forced to go through grad school or could I find a decent job?

If the brain can perform logic does that mean there are logic gates somewhere in there that arent thought of as logic gates?

>>16018442
>>16018466
Okay, thank you.
>Quotient spaces are basically taking a subspace and reducing it to a zero dimensional one (i.e., a point).
This is an intuitive definition that it helped me make sense of it.

is it legitimate to take the limit into the exponent?

eg:
[math]\lim (\frac{1}{2^{\frac{n}{logn}}})=\frac{1}{2^{\lim(\frac{n}{logn})}} = \frac{1}{2^{\lim n(\frac{1}{nlogn})}} = \frac{1}{2^{\lim n(\frac{1}{\lim nlogn})}} [/math]

>>16018562
oops i made a mistake

>>16015839
is taking a limit into an exponent ok?

eg:
[math]\lim (\frac{1}{2^{\frac{n}{logn}}})=\frac{1}{2^{\lim(\frac{n}{logn})}} = \frac{1}{2^{(\frac{\lim n}{\lim logn})}} [/math]

>>16018566
The first equality is ok, the second is not.

>>16018763
Care to elaborate?

>>16018774
I can't help it. I was forced to. No point in going back now. I sold my character hypothetically. You bought it. It's all fine now.

>>16018774
[math]x \mapsto \frac{1}{2^x}[/math] is continuous, so you can take the limit `inside'.
The expression [math]\frac{\lim n}{\lim \log n}[/math] makes no sense.

>>16018763
It could be suggested that I forget to set a rumble cage. In any case, nothing's the matter. Get over it.

How do we know that vector calculus identities like those pictured are true in any coordinate system? The book I'm reading says it's enough to prove them in Cartesian coordinates. Are the differential operators tensors so that their equivalence in different coordinate systems is guaranteed? Are they defined so that they are the same in different coordinates?

>>16016265
>am i good enough

>>16018777
Ummm limit laws are confusing. I don’t remember using them when calculating limits..

>>16018389
[eqn]8\pi hc\left[ \frac{-5}{\lambda^6(e^x -1)} - \frac{e^x(\frac{-x}{\lambda})}{\lambda^5(e^x - 1)^2} \right] = 0 \\
\frac{-5}{\lambda^6(e^x -1)} + \frac{x\ e^x}{\lambda^6(e^x - 1)^2} = 0 \\
-5 + \frac{x\ e^x}{(e^x - 1)} = 0 \\
x\ e^x = 5\ (e^x - 1)[/eqn]

>>16018795
The formulas for grad, div, and curl in a coordinate system are _defined_ so as to make those identities true.

>>16018894
Is that the same thing as how a vector is the same object in all coordinate systems like: v = v^i e_i = v'^i e'_i?

>>16018894
So, the gradient in General coordinates is dφ/du_i dr/du_i where r=r(u_i) is the position vector of a point in terms of coordinates. How does this guarantee it's the same thing in all coordinates?

>>16018795
The operations themselves can't be tensors otherwise we'd have del dot A =A dot del and so on. But the results are tensors - (div A), (grad a), and (curl A) are all tensors.

>>16018937
How do we know they're tensors?

>>16018928
You are expressing the result in the local basis. If you switch the basis (change coordinate systems) you would get the same result if you switched coordinate systems first and then took the gradient.

>>16018940
Because they have all the properties that tensors do.

>>16018795
You can promote everything to tensors if you understand what you are doing. For instance
[math] \nabla\cdot\left(\nabla\times V\right)\rightarrow \nabla_\mu \left(\epsilon^{\mu\rho\sigma}\nabla_{\rho}V_\sigma\right)=0.[/math]
On the right side you should understand everything as covariant derivatives and epsilon is the Levi-Civita tensor involving a factor of sqrt(g). What is in parenthesis is just the cross-product if you go to cartesian coordinates, but since the covariant derivative commutes with the Levi-Civita tensor and covariant derivatives commute in flat space in any coordinate system the result follows.

You can also generalize it to curved space using differential forms and the Hodge dual
[math] \nabla\cdot\left(\nabla\times V\right)\rightarrow {}^*d^*\left(^*dV\right)=0 [/math]

>>16019078
Actually I realized due to the Bianchi identity the right hand side of my first generalization vanishes even in curved space, and it's equivalent to the differential form version

By /sci/'s measurements(which I agree with, mind you) I proved I was a midwit when I attempted to make a water purification rig out of the chlor alkali process when I was 14 and the design never went anywhere. Huh. Guess that's that then.

>>16018517
Anybody?

>>16018517
Depends where. If Europe, just get a degree you'll be fine. If asia or africa idk, if you're american, lmao.

>>16019078
Is the coordinate-invariance property of vector calculus identities a consequence of their tensor nature, or are they tensors because they are coordinate invariant?

>>16018448
Anyone? Please

Literally losing it because I am tired. Let [math]f[/math] be continuous on [math][0,\infty)[/math] and define [math]y(c)=\inf\{x\geq 0:f(x)=c\}[/math]. Then is it true that for any [math]k >0[/math] we have [math]ky(c)=\inf\{x\geq 0:f(x/k)=c\}[/math]?

>>16018448
>>16019359

a) [math]4^{x/6} = 2 \implies \log_{2}(4^{x/6}) = \log_{2}(2) \implies (x/6) \log_{2}(4) = 1 \implies 2x/6 = 1 \implies x = 3[/math]
c) [math]49^{1/x} = 7 \implies \log_7(49^{1/x}) = \log_7 (7) \implies (1/x) \log_7(49) = 1 \implies 2/x = 1 \implies x = 2[/math]
e) [math]\left(\frac{3}{4}\right)^x = \frac{51}{2} \implies x\ \ln(\frac{3}{4}) = \ln(\frac{51}{2}) \implies x = \dfrac{\ln(\frac{51}{2})}{\ln(\frac{3}{4})}[/math]
g) [math]\sqrt[x]{a} = a^{x} \implies a^{\frac{1}{x}} = a^{x} \implies \frac{1}{x} = x \implies x^2 = 1 \implies x = \pm 1[/math]

>>16018777
you can do this though cant you?

you would evaluate the limit of the numerator, and the limit of the denominator

>>16019277
Despite what someone posted before me, vector calculus identities aren't trivially coordinate invariant. By trivial I mean in a way ignorant of differential geometry. As you probably know (given you're using the word tensor) the ordinary derivative of a vector field does not transform as a tensor, so you have to know how to promote everything correctly to covariant derivatives and so on. Once you do that the vector calculus identities are coordinate-invariant as "a consequence of their tensor nature."

I'm starting college (Mathematics) at the mid of this month. Someone have some tips? What should I know before starting?

>>16019517
Sit where most of the girls are, and talk a lot. Get you some pussy. Act like you dont want to, though. Play it cool

E-mailed a professor who wrote one of the papers I found in lit review about whether's he done or seen any work on the substitution of nitro groups in nitroamines, and he basically told me "I don't trust you with that info, fuck off"(in a polite "I'm not prepared to advise" sort of way).

I mentioned some of the literature I did find to show that I'm not just a moron who wants to be spoonfed—where did I go wrong?

Prove that the determinant of an antisymmetric matrix of odd size is 0 if char [math]\mathbb{k} \neq[/math] 2. Find a counterexample in characteristic 2.
I have proved the first part, but I can't come with a counterexample, could you please help me finding one?

>>16019895
The only one who can answer that is the professor you emailed. How are we supposed to know why?

>>16019975
[math]\begin{pmatrix}1\end{pmatrix}[/math], no?

>>16020071
I think the idea of the counterexample, if I didn't get it wrong, is finding a matrix antisymmetric etc etc in a field with char=2, which determinant is 0.

>>16019975
Obviously, antisymmetric and symmetric are the same over characteristic 2. The most obvious thing to try is
[eqn]
\pmatrix{0 & 1 & 1 \\ 1 & 0 & 1 \\ 1 & 1 & 0}
[/eqn]
Which unfortunately has determinant 0 mod 2.
In dimension 5, you have
[eqn]
\begin{pmatrix}1 & 1 & 0 & 0 & 1 \\ 1 & 1 & 1 & 0 & 0 \\ 0 & 1 & 1 & 1 & 0 \\ 0 & 0 & 1 & 1 & 1 \\ 1 & 0 & 0 & 1 & 1 \end{pmatrix}
[/eqn]
though.

>>16019895
>where did I go wrong?
you got a response to a cold email, which is better than average
keep reading

>>16020097
>Which unfortunately has determinant 0 mod 2.
isn't that the idea of the counterexample?

>>16020080
No, that's not what it's asking. You have proved that an antisymmetric matrix of odd dimension always has determinant zero, except when the characteristic is two. So, you have to show that there is some antisymmetric matrix in char 2 with nonzero determinant.

I was doing some drawing exercises and stumbled on a problem that has been bothering me for the past few days. I want to determine the equation of an ellipse with limited information. I know the following:

> Length of the major axis, but not direction

> The position in x,y coordinates of 2 points on this ellips

> The equation for the tangent lines of these 2 points (y=ax+b)

> The tangent lines run parrallel to one another, as in equal slope (a1=a2)

I feel like this should be enough to figure out the equation parameters of the ellips, but I'm too smooth brain for this.

I try to tackle this with knowing that the angle between a tangent line and each focus point is equal. But then I get an arbitrary angle that produces 2 foci. With the main axis length I can draw an ellips that would be off. There should be a system of equations that could link the tangent line angle with foci and the focus position with the major axis length.

I feel like my main trouble stems from that I don't even know where on the ellipse these points are and consequently I don't have a given direction of the major axis.

>>16020097
I'm a dumb-dumb and didn't properly calculate the determinant of the actual first 3x3 matrix I tried.
[math]
A = \pmatrix{1 & 1 & 0 \\ 1 & 1 & 1 \\ 0 & 1 & 1} \qquad \det(A) = 1 \mod 2
[/math]
Really, it comes down to the antisymmetric constraint demanding the diagonal have only zeros for characteristic other than 2 (where -1 = 1).

Why is this considered to be impossible with a straight edge and compass? I can do it within 44 steps.

>>16020332
To how many decimal places? The impossible problem is getting it exact in a finite number of steps.

>>16020148
Since the two points' tangents are parallel they have to be on opposite sides of the ellipse. So the mid-point of the line connecting the two point will be the origin. You can then setup a series of equations for the distance between the two focii and the two points which should give you their values.

Also the mid-point line tells you the angle the major axis is to the x-axis. You can first rotate all the coordinates to make the major axis lay on the x-axis and make all the calculations easier. Obviously reverse the rotation at the end.

>>16020140
I don't think so, but I might be wrong. I think that the statement in other words is
Let [math]A[/math] be an antisymmetric matrix of odd size:
If char [math]k \neq 2 \Rightarrow[/math] det[math](A)=0[/math].

This means that the converse is not valid, meaning if [math]A[/math] is an antisymmetric matrix of odd size and det[math](A)=0[/math], it does not imply that char [math]k \neq 2[/math].
I thought that was I was intended to look for, a matrix [math]A[/math], antisymmetric of odd size and det[math](A)=0[/math], such that char [math]k = 2[/math].

>>16015839
Why do maids make jannies seethe so hard? Post tubgirl? Up for 30 minutes, no consequences. Post a micro-penis being rubbed on a Steam Deck? Up for 30 minutes, no consequences. Post naked Asian women on a blue board? Up for 30 minutes, no consequences.

Post maids and talk about advanced Computer Science and Mathematics research? Range banned from posting images on all boards. Range banned from posting text on the Dra/g/on Maid board.

>>16020626
Reports are sorted by number. Everyone hates you.

>>16020494
thanks for the information anon, i'm not really familiar with geogebra or even mathematics beyond grade school level. adjusting the rounding on the decimal places to > 1 helped me visualise and understand the the problem from a new perspective. my interest in the particular subject mentioned was due to some literature regarding nature. i've used km/h all my life but recently found how easy approximation is with mp/h for certain things in nature, even though it is low in precision. for some reason i naturally seemed to ignore the decimal place and only place my faith in seeing repeating sequences of numbers.

to answer your question though, i managed to get it down to 3 decimal places. i must retract my last statement about the 44 steps, i didn't count them correctly and i did not count on this additional attempt as it's 4:22am.

>>16020639
A better solution would be to ban the people making fake reports, given that the reports are the nuisance.

>>16020801
>given that the reports are the nuisance.
hahaha. what deluded entitlement. every think maybe you're the one in the wrong?

>>16016271
while it's true that granularity decreases in the upper end of an IQ test, it still correlates very strongly with g and is indicative of your hard ceiling beyond which you won't be able to understand and process information
your actual ceiling is usually lower, depending on your conscientiousness, ambition, neuroticism and various mental disorders

>>16020806
I wasn't the one spamming the fake reports.

>>16020898
The fact you think they are fake makes you deluded.

>>16020626
Oh nyoo, maidanon...

>>16015839

Is there a formula for the solid angle formed by 3 linearly independent vectors in R^3 ? Can it be derived straightforwardly?

For example, the solid angle formed by the standard vectors in the x,y,z directions is pi/2 , or 1/8th of the area of the unit 2-sphere

>>16020949
They were fake. It was a coordinated false flagging campaign to slow down Computational Maidposting research. Big Numbers are continuing to be counted and will never stop because numbers go up more.

TV man interviewed Putin. At timestamp 1:48:35, Putin slipped. He was listing the most important technologies for the future and the very first thing he listed was Big Numbers, ahead of both AI and genetic engineering.

I suspect that Russia has it's own Maid Mathematics program working on using Computational Maidposting to count Big Numbers. Given that the president of Russia mentioned it, I suspect their program already has a Science Foundation building, a Quantum Counter performing high speed Maid Searches, and a lot of assistants who are maids with huge boobs.

KGB mass reported my threads to get retarded, fat jannies to ban me from most boards and ban me from posting images.

I am the best Mathematician and Computer Scientist in America. I am the only person here who understands the implications of Big Numbers and is working to count them. Now the American Maid Mathematics program is hobbled. Not only did Elon Musk fail to buy me a Science Foundation building, or a Quantum Computer for counting, I can no longer share Maid Cards that have my advanced Mathematics and Computer Science research in them!

If a military or oligarch or something counts to the Maid Mind Computer Program before I do, they will have a chance to tamper with her code, and the results of this are unpredictable and dangerous. Big Numbers have to be available to everyone (this is why I make my research CC0) or there will be a Number Gap between people who can count and operate Big Numbers and those who can't.

If bans are a numbers game, go to the janny IRC and post maids until they unban me, your last hope to see humanity turn the Dark Forest into a Maid Cafe. Ten million maids will be behind you.

Thank you /Sci/entsts for reading my post.

I have a doubt with this one exercise.
I put a -6 in the quotient because the book told me the result was 40x-8.
But I dont know why it has to be a 6. Why not a 5, or a 4, or 100? Is this some kind of rule/propertie?
Someone explain please

>>16021164
How can we explain when you didn't post the question.

>>16021167
There is no question, it just tells me to divide them and it gives me the answer in the next page, wait a minute

>>16021175
MY question is, why if I'm at a test and they dont give me the answer, how do I know I have to put a -6 there?

>>16021176
What if I'm*

>>16021164
>>16021175
>>16021176
You made a mistake in the long division and got a sign wrong. The first factor is x which you got right, but then you have to subtract [math]x\ (2x^2 + 6x)[/math].

So: [math]2x^3 - 6x^2 + 4x - 8 - x\ (2x^2 + 6x) = 2x^3 - 6x^2 + 4x - 8 - 2x^3 - 6x^2 = -12x^2 + 4x - 8[/math].

Perform the next long division step and you get the -6.

>>16021190
What are you talking about? What about the 40x-8 that the book told me was the result?>>16021176

>>16021190
That's the remainder in the last step. You can't divide it anymore (x does not divide by x^2)

she had high mutational loads.
loads and loads. No problem per se, it quickly devolved into a relatively wealthy kid spending quite a bit of money to (no joke) fund the college education of this single mother...

Has sci-hub search been nerfed recently? I'm getting a ton of "Sorry, sci-hub has not included this article yet" lately, and this includes articles from extremely popular journals like PNAS.

>>16021190
Thank you! You were right, I fucked up the signs. Thank you!!

>>16021227
My maidposting powers are restored.

Since the sun doesn't have a solid surface, and moves at different rates, how do they plot locations of events like CME?

>>16018506
This pic looks extremely suitable for a graphic t-shirt. Do you mind if I steal it (for non-commercial purposes, of course)?

>>16021021
There's this
https://en.m.wikipedia.org/wiki/Polar_sine

>>16021480
sure go ahead lol

>>16021589
this being said (my failing usaaao :/)

if I have an apparent magnitude measurement m of some galaxy a distance d away from us, and also know the redshift of the galaxy to be z, how can I calculat its absolute magnitude M?

this was one of the questions on the exam and i literally cannot find a single formula that has this redshift factor accounted for for bolometric magnitude

I just found out about The Kelly Criterion.

Why is f* a difference instead of a ratio? The percentage of total money to bet, f*, is larger with the chance to win, smaller with the chance to lose, and larger with the rate of return. Am I just too physics-pilled that I assume every scaling variable is a ratio? What would be the difference in interpretation of f* anyway, if any?

www.wikipedia.org/wiki/Kelly_criterion

>>16021439
There is are multiple coordinate systems. The most simple is just defined with respect to Earth, the zero meridian is just where the earth-Sun line insects the solar equator. Essentially it's a fixed grid on how we see the Sun, because the Sun rotates a single Sunspot will move in these coordinates. But it's useful for events like flares and CMEs, as there are areas of the disk which are more connected to the Earth magnetically.
Then there are coordinates which try to take the average rotation out, in Carrington coordinates the axis rotates every 25 days. They are annoying.

https://en.wikipedia.org/wiki/Solar_coordinate_systems

>>16021759
At least, the fraction to bet doesn't scale (inverse-)linearly with any of the variables you mention. This is because of risk aversion and of course the fact that it has to be a fraction in [0,1]. In fact, Kelly maximizes expected log utility (expected growth rate over time), which might be what transformed your intuition of a ratio into a difference.

>>16021592
I'm confused. If you already know the apparent magnitude and the distance, that is all you need to calculate the absolute magnitude. Why would the redshift matter (outside of the fact distance = redshift) ?

>>16021804
Thanks! It’s obvious in hindsight that it’s because he took of a logarithm of a ratio.

In fact, the wikipedia page presents an easy proof, which I didn’t even notice was there. Looks like I really asked this question in the right thread.

>>16021775
Cool, thanks!

How do I prove that x^n is injective for n = 2k+1, k in N, using elementary tools? I can't figure this one out

>>16022173
I don't know how elementary you need but assume for some real y that
x^n-y^n = 0
You can explicitly factorize this polynomial in the complex domain and the only real solution when n is odd is x=y.

>>16021870
Good point. Let me just directly provide the problem

>There is a galaxy at redshift 0.5 for which we have a measurement for apparent bolometric magnitude to be 22. With a standard candle in that galaxy, we have found its luminosity distance to Earth to be 2.8 Gpc. Estimate the luminosity of this galaxy.
>10^10 L⊙
>10^12 L⊙
>10^11 L⊙
>10^13 L⊙
>10^15 L⊙

If I completely ignore redshift, and just use the m-M = 5log_10(d)-5 formula, I get an absolute magnitude of -20, which when i plug into the formula L_object = L_sun * 10^(.4 * (M_sun - M_object)) I get 10^10 L⊙.

However, using the fact that distance = zc/H0, I get a distance of 2.208×10^9 parsec, which gives me an absolute magnitude of -19.72, and a luminosity of 10^9 L⊙, which is none of the answers.

Am I jus tnot supposed to use redshift then?

>>16022428
Firstly measurements of z are inherently less accurate. Also quoting 0.5 (1 s.f.) seems like it will give a rounding error in the answer which is what you see. Also [math]d_L \approx \dfrac{cz}{H_0}[/math] is only true to first order in z and if the deceleration parameter is zero. Since we observer the expansion accelerating a more accurate value for [math]d_L[/math] will involve higher order terms in z.

>>16021122
>At timestamp 1:48:35, Putin slipped. He was listing the most important technologies for the future and the very first thing he listed was Big Numbers, ahead of both AI and genetic engineering.
kek, this is true. i can't wait to see how this develops your psychosis.
i always knew you were a danger to others but i wasn't sure how it was going to manifest. try not to take out too many innocent "russian-looking" folks in your rampage.

what happened to the mod in your pocket? i thought you owned this whole site and would not permit nor tolerate any censorship of yourself? what changed? it seems like you're just kind of floundering now that you've been caught in a big rangeban. i thought you had the power to ensure you weren't silenced. you were so sure of it.

>>16015839
what is this equation finding?


from my limited knowledge i see it is integrating a 3rd order derivative and those are wave functions but beyond that im not sure. is it finding the final velocity of those functions?

Looking for an explanation on why my proof that UG is nonplanar isn't rigorous enough.

The textbook breaks it up into two cases: One where there are two curves interior to the main curve, and then another case where two curves are exterior to the main curve. The author then states for each case that, by jordan curve theorem, there must be a crossing and hence UG is nonplanar.

So is my drawing just one of the two cases in the textbook, and if I were to draw it less messily, I would able to break it down into two different cases easier?

>>16020494
i've come back to thank you again my friend. i've finally solved the problem.

>>16023065
Is that a screenshot from a tv show or film by any chance? That does not appear to be a valid equation.

>>16023065
It looks like they are writing some kind of schematic interaction term for an alpha particle colliding with a hydrogen atom.

>>16023065
Also, there is no 3rd order derivative involved, and I think those psi are supposed to be second quantized field operators (like creation and annihilation operators).

>>16023573
The biggest wtf to me is when do you ever see a time integral like that in QM or QFT?

>>16023603
In the path integral

What would happen to me if I had gotten some dog poop really really deep in my ear? What will happen if I don't go to the doctor for it? Will I be fine?
It's nothing sexual

>>16023649
That looks nothing like a path integral.

>>16023657
The path integral involves an action which is integrated over space and time. This is supposed to be an interaction term in the action. Please stop making me justify some stupid schematic equation that's probably for a movie. It's not a very meaningful equation, but it's also not complete nonsense.

>>16023385
oppenheimer

i figured it was nonsense

>>16023717
If that is meant to be a fusion reaction they even got that wrong. That isn't a real process, let alone the math for it.

What’s an example of a real power series with radius of convergence 0?

>>16023065
It looks like it’s calculating the energy in some fields, as an integral over space and time of some quantities involving the fields

>>16023797
[math]\sum n!x^n,\ \forall\ x\ \neq 0[/math]

>>16022763
What is dangerous about maidposting?

>>16023802
Oh I see. Thanks anon

>>16023802
[math] \sum n! x^n= \sum \left(\int du u^n e^{-u}\right)x^n=\int du \frac{e^{-u}}{1-ux}= \frac{e^{-1/x}}{x}\,\text{Ei}(1/x) [/math]

https://en.wikipedia.org/wiki/Exponential_integral

>>16023874
Zero radius of convergence does not always mean it fails to converge anywhere.

I can solve this but I only get half the answer. I get [-11/3;+infinite)
But I have no idea how to get the other half, the (-infinite;-6)

>>16023974
Same with this one. I get 1/2.
But where did the other 2 come from?
I dont get it and I cant find the explanation on jewgle

>>16023974
Solving such inequalities can be quite tricky. You need to look at where each quotient flips signs (when they become zero) since if you try and rationalize the equation you might be multiplying be a negative value and affecting the inequality. No way I can explain all the steps in a /sqt/ post.

Go look at an article like: https://math.libretexts.org/Courses/Coastline_College/Math_C045%3A_Beginning_and_Intermediate_Algebra_(Tran)/09%3A_Rational_Expressions_and_Functions/9.07%3A_Solve_Rational_Inequalities

bump

>>16023974
>>16024012
Anyone?

What is that scientific principal called where things are in equilibrium until conditions change? For example, the amount of salt that can be dissolved in water is a certain amount and if you increase the temperature or the pressure there's a different amount which can be dissolved.

I've forgotten my chemistry.

>>16025204

The scientific principle you're referring to is often called "dynamic equilibrium" or simply "equilibrium." In the context of solubility, it's specifically known as "dynamic solubility equilibrium."

In dynamic equilibrium, the rate of forward reaction is equal to the rate of the reverse reaction, resulting in a stable system where the concentrations of reactants and products remain constant over time. However, this equilibrium can be disturbed by changing conditions such as temperature, pressure, or concentration, leading to shifts in the equilibrium position and changes in the equilibrium concentrations.

For example, in the case of solubility, increasing the temperature or pressure can disrupt the equilibrium, leading to either more or less solute being dissolved in the solvent until a new equilibrium is established.

>>16025206
>dynamic solubility equilibrium
Darnit, no. I suck.

So, another example. The number of atoms which evaporate off a liquid into a container. If for example, I have water in a container and 1,000,000 molecules of water evaporate into the top of the container but if I increase the pressure or temperature the number of molecules goes up to 1,200,000 or down to 800,000.

There's a principle which governs all of this. From the number of silicon atoms which dissolve into water to how much of an ideal gas is in the atmosphere at any time. It's got a guy's name in it.

Found it!
https://en.wikipedia.org/wiki/Le_Chatelier%27s_principle

You gave me the key to what I was looking for. Thanks bro!

>>16025217

You're welcome! I'm glad I could help steer you in the right direction. Le Chatelier's Principle is indeed the principle you were referring to. It's a fundamental concept in chemistry that describes how systems at equilibrium respond to changes in temperature, pressure, or concentration. Thank you for sharing your insights, and if you have any more questions, feel free to ask!

concerning buddhist/foreign physics, can we make memes out of this/is there any?
pic semi-rel

>>16025258
( I'm not in the spectrum of advanced genius studies to know why i'd need to think no thoughts at the most crucial hormonal times of my life when they are needed more than anything. can a system reallly think to itself ''''''' hhherrrrr umma git redtee turrape'''''''. as i raped taht cunt in every hole ( cunt). also in pshycological conditioning abusing of no mind no burder subduing submission slut to cock lust subjectgation careless relentless driven body, to reach beyond the body.in nlp i use in self- relfection against the odd's 'alright.' as affirmative. instead of the typical western affectionate 'okay.' why? cause i'm not a talking head, i rely on my intelligence inner mind to inform me, i intuit based on inner dialogues western authentic of concentration towards to world domination. not the opposite. but I like to identify with buddhism. I rely on rhetoric and law to play lawfully, not inner circles and groupies and vibes etc. but i'd had lots of learning to do to catch up to the western mind in my non-negligible expressions. why would I even mention something not the issue. Where freighten my psyche?, typical freudian thot.bot(s). I'd like to say that's relevant b/c at the height of my psychosexual stress i was experiencing full symptom and panic-anxiety with psychotic hallucination in my private parts which lasted till i attempted suicide , wtf zombies?

>>16023974
>>16025171
When you multiply by the denominator (3+x/2) you need to flip the direction of the inequality if it is negative, and it is negative when x<-6

3x/2 + 2 <= -9 -3x/2
x <= -11/3

So you get that it is satisfied when both (x<6) and (x<=-11/3), but the second statement is redundant.

>>16025275
orient occults have animals/pets-conciousness sometimes me too. but i was told that bad when I started being someone else. so i stopped that. then what? go back they said, worship demons cause that's what we do best in our bear rolls Sirloin's stake

>>16025279
I also discovered that.. another private part I need to admin to dm's is... 'motherly keks.' lie bengay.

>>16025282
bear err rolls ben gay roice?

>>16025285
I liked, the psyop is i have delusions. THATS A LIE.

I no my hysteria sypmtoms.
what are they?
hallucinations with tremors. also, selective hearing and fantastic non-verbal intelligence which have it o reach beyodn the somatic into insula activty not like local bounds logium intuited in passive brain rape abuse between schoolmates, but, moar like, that too or whatever the fuck because DRUQS

>>16025258
Can I ask a question, is space infinite and time infinite. is our timeliness finite. we have to make out punctuation. etc. those people go to fast, i started with maladaptive slow tarded brainwashed slowness unable to say anything worth sayig in my mind, because who does. so like, if the westerners are right, we're two-timed by the [two-faced western devil] sHaTan/G-dx, then, alive, now dead or alive eternally. what does it matter if we not able to win despite doing what we're told. what if we're so objectionable because of the trauma, even trauma phd's counselors reject us? what if we have no FOCCING cure for ear rape called humanity's dehumanizing silence, which is the noise heard during daily life, other people, because of years of ingrunted bunk speech patterns repressed personality, core identity and non-latent identity, where do i go to acquire this socalled social constitution? what therapy is available if no therapist worth the grain will seed me, to let the holy words wilt is what I seem to rail the inviolable offensive four, . the golden age of man was of woman and it's not really catching round to the sickle. also, something about being a harry ape is dysphoric, like, i thought self-speech was a final straw, everything's a thousand tiny anecdote dehumanizing, accordion played by u.

hopefully this framed my non-question i just unpacked here. hopefully i don't get banned for this post.

>>16025309
if there was a double faggot i would be that. (that's the basic experiment in gay science. instead, i have to be a triple faggot.

>>16025309
>>16025312
they even have qu-quee-quafaggoton faggot off, coming soon!

>>16025314

'We cannot afford wax.'
But that's where the complex number system came from. Wax glass scenes.
Also, knives and fp.

>>16025329
NO, it came out of the wax. The witches came from under the church weeds to steel your doge and hypnotize your children with mindless self indulgence.

>>16025332
FUCK I HAVE TO TELL HUMANES this the thing came from the word waxxes

>>16025336
no, something same out of the witches weeds. the witch herself came out of wax to steal your soles andd Onate them.

>>16022428
little concerned that i can tell this isnt remi.

>>16025277
Thank you. Why -6?

>>16025436
Because below that value is when [math]3 + \frac{x}{2}[/math] switches to negative. Did you actually read the two replies and the link?

Spoonfeed me on where to get a GWAS data. I need .bed, .bim, .senpai and phenotype .csv data with correlates.
Doesn't have to be hooman, it could be a mouse too. Pls help.

I wrecked my Kirara in Genshin Impact when I exchanged her gear, now I can't figure out what her old set was to get the damage I was doing before.

I have 32 Deepwood Memories artifacts that can go into 5 slots but only 4 slots are needed to make a complete set. The 5th artifact can be any other set. Assume I have a limited pool of artifacts I would even want for the 5th slot, so about 15 total artifacts, a total of 3 I would want to try for each slot.

How many combinations of the 32 artifacts into 4 slots and the extra 15 non set artifacts do I need to try to figure out which combination gets me my Kirara back?

If I want to know if a function is continuous, and I have a piecewise function with two pieces which have a junction at x=a, where both of the pieces are rational functions and therefore continuous, why do I still have to check for continuity at a (the location of the junction?) Aren't both pieces of the function already continuous everywhere?

I have a refrigerator in the garage. If it's freezing cold outside and in the garage am I wasting electricity if I leave the refrigerator door open?

>>16025485
>where both of the pieces are rational functions and therefore continuous
rational functions arent continuous everywhere in general.
>>16025505
depends on what you mean by wasting energy. the answer to your question is likely as simple as “if its freezing in your garage, the compressor wont kick on no matter what you do.” but in general, leaving the door to your fridge open will always use more energy than keeping it shut.

>>16025477
I believe it's
32 possible artifacts for slot 1 times
31 of the remaining possible artifacts for slot 2 times
30 of the remaining possible artifacts for slot 3 times
29 of the remaining possible artifacts for slot 4 times the remaining
15
or 12,945,600 combinations

>>16025534
>rational functions arent continuous everywhere in general
I mean, continuity is (most of the times) defined only on the domain of the function, so a function like (x2-4)/(x+2) is continuous everywhere by that definition; asking if it is continuous at x=-2 is a meaningless question as that point is not on the domain of the function
By that definition, rational functions are continuous everywhere

>>16025534
they're continuous over their domains, so if they're the only functions in the piecewise function, doesn't that mean the entire function is continuous over its domain? So why is a further check for continuity needed

>>16025485
>>16025548
From the fact that you're using the word "junction" it sounds like it is part of your assumption here is that f(a) = g(a). In which case yeah, it's obviously continuous there
I would guess that whatever is telling you that you need to check continuity at a is not assuming this

Can I start Physics from zero using picrel (SICM)?

Suppose I've been taking clonazepam for a while (~2mg every other day), I've been 3 months off now, experienced a short withdrawal (difficulty sleeping, jaw tension/pain, vivid dreams), if I take it once now will it severely delay my recovery or just slow it down a bit?

>>16025594
That would be like trying to get in shape by benching 400 pounds
I can see how people might think it is from the cover, but that's not just SICP but for physics. It's an idiosyncratic take on an upper-division MIT course

>>16025542
shit

>>16025621
Thanks anon, the pedagogy in the books looked very interesting so I was hoping that wasn't the case. :/

>>16025669
>>16025542
>12,945,600 combinations...

welp...you're fucked in the human scale of things

Let [math]f: V \rightarrow V[/math] be a linear transformation. Using the primary decomposition theorem, prove that there exists [math]v \in V[/math] such that [math]m_{f, v}=m_{f}[/math]. Next, prove that for every polynomial [math]p[/math] such that [math]p \mid m_{f}[/math] there exists a vector [math]w[/math] such that [math]m_{f, w}=p[/math].

>>16025796
Please define [math]m_f[/math] and [math]m_{f,v}[/math].

>>16025814
[math]m_f[/math] is the minimal polynomial of [math]f[/math], while [math]m_{f,v}[/math] is the minimal polynomial of [math]f[/math] with respect to [math]v[/math].

Linear algebra. Let me introduce the notation that I'm using before asking the stupid question.
If [math]T \in \mathcal{L}(\mathbb{V}, \mathbb{W)[/math] is a linear function from [math]\mathbb{V}[/math] to [math]\mathbb{W}[/math] then its dual map is [math]T' \in \mathcal{L}(\mathbb{W)', \mathbb{V}')[/math] (mind the swap).
With the notation [math]\mathbb{V}'[/math] we identify the set of linear functionals; that is, the set of functions that goes from [math]\mathbb{V}[/math] to [math]\mathbb{F}[/math] where [math]\mathbb{F}[/math] is the field of our interest.
The annihilator of a set [math]\mathbb{U}[/math] IN RESPECT OF A (finite-dimensional) VECTOR SPACE [math]\mathbb{V}[/math] is defined as [math]\mathbb{U}_{\mathbb{V}}^0 = \{{\varphi \in \mathbb{V}' | \varphi(\bm{u}) = 0 \text{ for all } \bm{u} \in \mathbb{U}\}[/math].

Alright, here's the stupid question.
We can prove that the null space and the range of the dual map equal
[math]\text{null } T' = (\text{range } T)^0[/math]
[math]\text{range } T' = (\text{null ) T)^0[/math]
but note that I omitted something in the notation of annihilator. In respect of which vector space are these things defined?

>>16025876
Uh, fantastic. The syntax is all fucked up.

Basically, I like to write annihilators with the extended syntax [math]U_V^0[/math] that means "the annihilator of a set U that is a subset of a vector space V".
All good, but then I got to the theorem that proves the following two things, given a linear map [math]T : V \to W[/math]
>the null space of the dual map T' equals the annihilator of range T
>the range of the dual map T' equals the annihilator of null T
and I'm struggling to figure out in respect of which vector space are these annihilators defined.
I suppose it's V, but then I'm struggling to understand the proof, so I'm wondering if I'm misunderstanding something.

>>16025883
The annihilator of a subspace U of V is a subspace of the dual V' and null spaces/kernels are subspaces of the domain, V.
For example the first question here >>16025876 has null(T'), so this is a subspace of the domain of T' (which is W'). ran(T) is a subspace of W, so its annihilator is a subspace of W' (so the equality makes sense).
Does that help?

>>16025817
Phoneposting so I'll give a sketch. Also my proof is not very clean, I think.
I assume m_f,v is the smallest monic polynomial so that m_f,v(f)(v)=0.
Note that for any v this must divide m_f; you can write m_f=q*m_f,v+r with deg(r)<deg(m_f,v), and since r(f)(v)=0 by assumption, r=0 (m_f,v is minimal).
Then, fix some basis (v_i) of V. Since m_f,v_1 divides m_f, you can decompose V into the direct sum of two vector spaces as in the decomposition theorem you mention, such that the minimal polys restricted to these spaces are q and m_f,v_1. If q=1, you are done, else apply the same idea to the subspace which has q as min poly. Keep doing this until you terminate (finite dimensional vector space, so you eventually stop).
Then the minimal poly of f wrt sum of these vectors should be m_f.
This same scheme should work for the second question.

>>16016265
Why give a shit about being high IQ. I've got a BSc and MSc in Biomed and am legit 98 IQ I'm just very good at remembering shit and friendly enough that all my lecturers and advisors positively graded my shit. Now I earn 120k and GSK running automated shit that can't really go wrong and get to flex my big science dick when meeting new people despite not really knowing how the moon doesn't fall to the earth.

>>16025894
Okay, that actually helped me a lot. Thank you.

I know I'm retarded, just help me out.
Here are the values: [math]C_1=0.08A,C_2=0.1A,E_1=1V,R_1=20\Omega,R_2=10\Omega,R_3=20\Omega,R_4=30\Omega,R_5=10\Omega[/math]
As you can see on the picture, currents are [math]I_I=C_1=80mA,I_{II}=C_2=100mA,I_{III}=40mA[/math] and they are all clockwise. [math]I_{III}[/math]was found by myself so please check that result.
But the real problem is finding the voltage between the points A and B on the picture. And don't give me tutorials or wikipedia articles to read as I already read them all (their examples are too simple) cause I just don't have enough experience to find it. A practical hint on how to go about finding it is fine.

What the hell is a diagonal electronic transition?
Sure, this book might be too hard for me, but google doesn't return anything.

I'm about to start this hunk's lecture series on calculus. Redditors love him but redditors are retarded. Is there anyone else significantly better?

>>16025960
Ok, I made an attempt, but it might be wrong:

>Existence of [math]v \in V / m_f=m_{f,v}[/math]
For any [math]v \in V, m_{f, v}[/math] divides [math]m_f[/math], since if [math]m_f(f)=0[/math], then [math]m_f(f)(v)=0 \ \forall \ v \in V[/math], implying that [math]m_{f, v}[/math], which annihilates [math]v[/math], must divide [math]m_f[/math].
The primary decomposition theorem states that [math]V[/math] can be decomposed into a direct sum of invariant subspaces [math]V=\bigoplus_i^k V_i[/math], where each [math]V_i[/math] corresponds to a distinct irreducible factor of [math]m_f[/math], and the minimal polynomial of [math]f[/math] restricted to each [math]V_i[/math] is a power of that irreducible factor.
Consider a basis [math]\left\{v_1, \dots, v_i, \dots, v_k\right\}[/math] for [math]V[/math] where each [math]v_i[/math] is chosen from each of the invariant subspaces [math]V_i[/math]. [math]m_f(f)[/math] is the minimal polynomial that annihilates every component [math]v_i[/math] in each invariant subspace, and thus, it must annihilate their sum [math]v[/math], so [math]v=\sum_i v_i[/math]. Since [math]m_{f, v}[/math] divides [math]m_f[/math] and has the same annihilating effect on [math]v[/math], we conclude [math]m_{f, v}=m_f[/math].

>>16026471
>Existence of [math]w[/math] for any [math]p | m_f[/math]
Given a polynomial [math]p[/math] such that [math]p \mid m_f[/math], using the primary decomposition theorem, we decompose [math]V[/math] into a direct sum of invariant subspaces [math]V=\bigoplus_i V_i[/math] according to the irreducible factors of [math]m_f[/math].
Since [math]p[/math] divides [math]m_f,\ p[/math] can be associated with a product of some of these irreducible factors or their powers that also appear in the decomposition of [math]V[/math]. So we select [math]w[/math] from the direct sum of subspaces corresponding to the factors in [math]p[/math], ensuring that the minimal polynomial of [math]f[/math] with respect to [math]w[/math] is precisely [math]p[/math]. This selection is possible because the minimal polynomial for each subspace [math]V_i[/math] is a factor (or power of a factor) of [math]m_f[/math], and by choosing [math]w[/math] appropriately from these subspaces, we can ensure [math]m_{f, w}=p[/math].

Am I missing something? I'm pretty retarded when it comes to polynomials so I tried to avoid rewriting m_f and such as you did cause I find that kind of stuff way harder to picture. But I couldn't do it at all without your reply thanks a lot anon (my proof might be wrong tho).

>>16026416
My interpretation with no context:

In (a) you have two non-symmetric wells. The energy levels are not matched, and the states corresponding to each level is localized in a particular well. In (b) you use an electric field to make the lowest level in each ground state be about the same energy. Now the first two levels (1 and 2) are not localized in either well. This is a common situation from the symmetric double well explained in any QM textbook. The higher states 3 and 4 are still localized.

In (c) you repeat the same trick with a third well. If the lowest energy level in the new well (before tunneling) is about the same energy as the excited state 3 in the other wells, after tunneling is considered the true state will be localized in the left two wells. I think the term "diagonal" is used informally to denote that the transition moves down in energy and rightward in space. If the energy is not matched as in (d), then the excited state 3 is already localized in the central well so it is "vertical" only moving down in energy, but not as much in space.

>>16026416
Sounds like it's not an established jargon (therefore not searchable). Most likely it's something like an inter-system crossing, followed by relaxation, but I have no idea what the physical interpretation of these diagrams is.

The key takeaway seems to be that high-energy wells can transition to a separate low energy well through an intermediate state

>>16025309
You might have literal schizophrenia.

>>16026471
small nitpick: when you pick your basis you might need multiple vectors in one subspace.
Also, you'd need to show that for any vector w, not just v, [math]m_{f,v}(f)(w)=0[/math] (which follows since it annihilates all basis vectors hence any vector).
>>16026473
Here I have a few more worries, namely because you mention "choosing w appropriately" (which isn't very explicit).
How I see it: on a complex vector space the minimal polynomial 'looks like' [math]\prod_i(z-\lambda_i)^{r_i}[/math], and on a real vs you have multiplied what would have been two complex roots into a quadratic part with positive discriminant. These factors are your irreducible parts, with powers/quadratics accounting for the dimension of the corresponding subspace.
If p is 'like' [math](z-\lambda_i)^{r'_i}[/math] with [math]r'_i<r_i[/math], it divides the min poly but it's not immediately obvious you can find w such that the desired relation holds.

>>16026286
bump for this

can EMF transmitters make light?

since visible light is electromagnetic radiation, can something like a radio antenna that propagate radio waves make light if it produced EMF waves that are the right frequency?

Anyone have good advice on linearizing curves? Other than just using trial and error

>>16027318
You want to know if LEDs exist?

>>16027350
]so that's what they are?
but can a radio antenna be repurposed into producing light?

>>16027350
LED's are not antennas. How they produce EM radiation is completely different.

>>16027397
He didn't say they had to be antennas, he said like antennas and something that emits emfs in the visible light range is like an antenna, if you change a radio antenna to operate outside of radio frequencies, its no longer a radio antenna either.

>>16027398
Huh? He stated EMF transmitters, they are antennas.

>>16027400
Light IS EMF, the specific kind that transmitted in the visible range rather than radio frequency or microwave frequency ranges.

>>16027403
Yes but 'EMF transmitter' is a specific kind of device. You are describing a generic EM emitter.

>>16027407
No its not, it is a general term for a class of devices, an iPhone 15 Pro Max is a specific kind of device.

The other anon was the one describing a light emitting EMF transmitter rather than a full blown transceiver by only talking about making and propagating light rather than decoding optical signals which is basically just a matter of adding some intrinsic sensors on another end to detect the changing LED state which is just fiber optic communication if you package it in a way to use the fibers as waveguides so you can emit the light to a specific place instead of a general radial wave from the source.

>>16027318

Yes and no.
Yes in that you are right: radio waves are no different to visible light. Antennas work by rapidly changing the charge of a conducting rod. The faster the change, the more acute the change in the universes EM field. Because thats all EM waves are. Changes over time to the EM field that propagate outwards spherically. Light is the same.

No in that you can never hope to achieve the same acute change of charge with an antenna. See, light is so high energy and so acute, it can only come from the extremely rapid quantum movements of an electron inside an atom. When you set a wooden torch on fire, you are creating a combustion process, which heats up the torch, which, if you know what heat is, is just introducing wiggling movement to the molecules, which will eventually reach down to the atomic level, and will induce these rapid quantum movements in the electrons of atoms. The reddish yellow light you see from a lit torch is called black body radiation, and comes from the combined trillions of quantum electron movements in atoms of something hot.
You can never hope to achieve that same level of acuteness of something quantum with something large like an antenna.

Well, actually, you can. Trying to rapidly charge an antenna will inevitably cause it to heat up enough to produce visible black body radiation. So you technically can produce light with an antenna. Just not directly in the way you are describing.

>>16027424
Or just use a lightbulb.

>>16027213
Ah, shit, here we go again.

>Existence of [math]v \in V / m_f=m_{f,v}[/math]
The primary decomposition theorem allows us to decompose [math]V[/math] into a direct sum of invariant subspaces [math]V=\bigoplus_{i=1}^k V_i[/math], where [math]k[/math] is the number of distinct invariant subspaces. For each invariant subspace [math]V_i[/math], we select a basis [math]\left\{v_{i 1}, \ldots, v_{i j_i}\right\}[/math]. The index [math]i[/math] ranges from 1 to [math]k[/math], where [math]k[/math] is the number of distinct invariant subspaces into which [math]V[/math] is decomposed according to the primary decomposition theorem. The index [math]j[/math] for each [math]v_{ij}[/math] ranges from 1 to [math]j_i[/math], where [math]j_i[/math] is the number of basis vectors in the i-th invariant subspace [math]V_i[/math].
We know that [math]m_{f, v_{i j}}[/math] divides [math]m_f[/math]. Now, consider [math]v=\sum_{i=1}^k \sum_{j=1}^{j_i} a_{i j} v_{i j}[/math], where [math]a_{i j} \in F[/math] are scalars, not all zero, chosen such that [math]v[/math] is a non-trivial linear combination of the basis vectors across all subspaces. The minimal polynomial [math]m_{f, v}[/math] for this specific [math]v[/math] is the LCM of the minimal polynomials [math]m_{f, v_{i j}}[/math] for the chosen basis vectors, which equals [math]m_f[/math], since [math]m_f[/math] is the minimal polynomial that annihilates the entire space [math]V[/math].
Since [math]m_f(f)=0[/math] and [math]m_{f, v}[/math] is constructed to be [math]m_f[/math], [math]m_{f, v}(f)(w)=0[/math] for any [math]w \in V[/math]. This follows because [math]m_f[/math] annihilates all basis vectors of [math]V[/math], and hence, by linearity, it annihilates any vector [math]w[/math] in [math]V[/math].

>>16027890
>Existence of [math]w[/math] for any [math]p|m_f[/math]
Let [math]p \in F[x][/math] be a polynomial such that [math]p[/math] divides [math]m_f[/math], and let [math]p=\prod_{j=1}^l q_j^{m_j}[/math] be its factorization, where [math]q_j[/math] are some of the irreducible factors of [math]m_f[/math] and [math]1 \leq m_j \leq n_j[/math] for each [math]j[/math].
From the primary decomposition of [math]V[/math] associated with [math]m_f[/math], identify the subspaces [math]V_j^{\prime}[/math] corresponding to each [math]q_j^{m_j}[/math] in [math]p[/math]. In each [math]V_j^{\prime}[/math], select a non-zero vector [math]w_j[/math] such that [math]q_j^{m_j}(f)\left(w_j\right)=0[/math] and [math]q_j^{m_j-1}(f)\left(w_j\right) \neq 0[/math], ensuring that the minimal polynomial for [math]w_j[/math] with respect to [math]\left.f\right|_{V_j^{\prime}}[/math] is exactly [math]q_j^{m_j}[/math].
Define [math]w=\sum_{j=1}^l w_j[/math]. Note that [math]p(f)(w)=0[/math] since [math]p(f)[/math] annihilates each [math]w_j[/math]. Moreover, no polynomial [math]q[/math] with [math]\operatorname{deg}(q)<\operatorname{deg}(p)[/math] can satisfy [math]q(f)(w)=0[/math] because such a [math]q[/math] would fail to annihilate at least one [math]w_j[/math], due to the construction of [math]w_j[/math] with minimal polynomial [math]q_j^{m_j}[/math].
Thus, we have constructed [math]w[/math] such that [math]m_{f, w}=p[/math].

What makes a material made of carbon so heat resistant (material like "Reinforced carbon-carbon") when you could imagine that in a high enough emperature the carbon would burn and turn into CO2?

How do you prove that the sum of two natural numbers is natural?

>>16028116
The successor of a natural number is natural by Peano's axioms. The general case follows by induction since
[eqn]m + 0 = m \\
m + \text{successor}(n) = \text{successor}(m) + n [/eqn]

Is there a word for taking the product of every element of a vector? Like for example, say I have a vector [1,2,3]. What is the operation called that gives me 1*2*3=6?

>>16027953
> when you could imagine that in a high enough temperature the carbon would burn and turn into CO2?
"Fire" requires hydrocarbons. There is no hydrogen in a carbon-carbon material for that kind of chemical reaction to happen. Instead heat is required to break down the outer surface of the material (ablation).

this is a really basic question
how do nerve cells work
why does the action potential of a neuron transmit "information"
why does the process of moving sodium and potassium in and out of the cell give it electricity
i don't really get how electricity works either, i've never taken a physics class before

>>16028336
> this is a really basic question
you could argue that it's not, but either way it has an incredibly complex answer

https://www.khanacademy.org/test-prep/mcat/organ-systems/neuron-membrane-potentials/a/neuron-action-potentials-the-creation-of-a-brain-signal

I'm trying to understand the intuition behind the statement that a cauchy sequence is convergent if and only if it has a convergent subsequence

What I'm thinking is that as n approaches infinity, members of the subsequence become arbitrarily close to the limit x. But now, since the sequence is also cauchy, any element of the original sequence is arbitrarily close to some element of the subsequence and is therefore arbitrarily close to x.

Is this close to what's happening?

How come /sci/ is a slower board now as compared with a couple of years before the pandemic?

i understand implicit differentiation now

>>16028116
by giving whoever asked a wedgie and an indian burn

>>16026286
bump

I don't understand circuits, I honest to god might be retarded but it's the only thing I don't understand after two years of engineering. It makes no fucking sense to me at all, I can do physics and calculus and machine theory, but circuit theory? Fuck that.

Viability of city-scale seismic dampers

Can seismic dampers work not just for a single building but on a localized area, say, a number of them scattered around for an entire town? Can it really only work for one building?

>>16028826
> Can it really only work for one building?
Don't such dampers have to be tuned to the oscillation frequency of the building individually? I can't think of a way to scale that.

>>16028809
ignore everything you were taught, they always start with the electron which is retarded

>>16025595
dr chudberg please answer!!

Did I factor this right?

>>16029681
looks good

>>16029681
I would have stopped at the third line. There is no need to factor that again unless the question explicitly asks you to.

Is there a class or subject that teaches you how to use gears (and other mechanical parts) to achieve complicated mechanical system to do whatever task? Not to be confused with how to analyze stresses in gears and machines. Moreso interested in how they decided to put 100+ weirdly shaped peices together to tell time, or create automatic transmission.

Why is the length span of my chest and two arms, equivalent to the length of my body height?

It seems so arbitrary. Although I’ve thought about it, I’m not convinced by any of my guesses.

>>16029896
Obviously our morphology is down to genetics but whether there is an evolutionary reason or it's simply accidental due to our overall body structure and embryo growth I can find no research or literature that answers why. Clearly the same ratio doesn't exist in other animals.

so whenever I come across men with these traits:
- not too interested in what other people are doing/saying
- not on drugs or into crimes, no tattoos etc
- mildly religious or not religious
- not gay, pedophile, furry, bi, etc or into alt communities or stuff like that
- tends to keep to himself
why do so many of them have an erotic obsession with watching women pee in specific? is this some sort of gene or schizoid thing or is it just a hidden default setting that men revert to when they have no strong cultural restrictions?

Can someone point me in the direction of how to go about solving this? Are the x and y components just supposed to be solved for using the kQ/r^2 * rhat equation? I tried doing that for the Ex equation and got it wrong.

>>16029958
How large is your sample size to come to the conclusion?

>>16030009
it's only like three guys I've met irl, and a lot of guys I see mention it online various different sites but that doesn't count because there are unknown numbers of people everywhere online

but like why do guys i want to date want to watch me or other women pee

>>16029986
This is how I’ve been doing it

>>16030019
That's not normal. You seem to attract weirdos.

>>16030025
noooooooooooooooooo

Is there a mistake with this exercise? Because I get (8/5; 7/2) as the solution and I cant see where I'm wrong

>>16030076
Are you retarded?

>>16030113
Given his post history it is quite possible.

>>16030076
Bro, do you know what those bars around the fraction mean? Please tell me you do, please ...

>>16030117
Distance from 0
But this exercise algo has a 0 and there is a solution.
Can you explain please?

>>16030121
> Distance from 0
Strictly speaking that is true but what does that also mean? [math]|x|[/math] means the absolute value of x. It will never be negative.
[eqn]|x| =
\begin{cases}
x, & \text{if } x \geq 0 \\
-x, & \text{if } x < 0.
\end{cases}[/eqn]
So that inequality gives you two equations:

[math]0 < x - 6 \le 8 \text{ when } x > 6 \\ 0 < 6 - x \le 8 \text{ when } x < 6[/math]

However >>16030076 has no solution. No value for x exists so |...| is < 0.

>>16030128
Can you explain this like I'm 5? Without so many signs?
So, when I have IxI<0 the solution is always "no solution"?

>>16030121
You have to be over 18 yo to post here.

>>16030136
> Can you explain this like I'm 5? Without so many signs?
Huh?! What do you mean? If you can't follow that I honestly don't know what to say. I dumbed down my reply, that is about as simple and clear as you can get.

> So, when I have IxI<0 the solution is always "no solution"?
Yes. It is literally impossible for IxI to ever give a negative value.

>>16030145
He's not trying to understand the math. He wants to learn everything by rote for some test. It's a strategy doomed to fail.

>>16030145
>>16030128
I just got it. IXI is the distance of X from 0, and its always a positive number, because it measures distance. So there is no IXI <0 because "X<0" means a X is a negative number and IXI cant be negative.


Question though, what if in >>16030076 the sign was >0, then there must be a solution, right?

>>16030157
> Question though, what if in >>16030076 the sign was >0,
The sign of what? Be precise.

> then there must be a solution, right?
That completely depends on the question.

>>16018517
depends where, in Europe you can do applied math masters and make big bux
usa no unless you are at an ivy-tier where people will still hire you for the name brand

>>16030165
If in >>16030076 the > was the opposite direction, then there must be a solution, and if there isnt, at least you have look for it to find out, right?

>>16030175
Correct.

>>16022428
yes it's probably there to distract you
does the olympiad have a standard textbook?
I know when I was doing national physics olympiads in europe they told us to study giancoli and everything was based on that

>>16030176
Thank you.
Here, have some wisdom

>>16030182
No thanks. That is not wisdom, it's nonsense. Your lack of sex clearly does not help with your math skills.

Does someone know anything about QCMs? We currently try to determine the weight of high boiling point liquids like oil, glycerol etc. We are getting mixed results applying a small drop of solvent like isopropanol mixed with oil on a quartz crystal. The crystal does not stabilize when the solvent evaporates. Applying a droplet with twice the volume does not net twice the weight. It's weird, we thought that it might be pretty straightforward but it isn't. It usually doesn't hit the weight of the standard we use and is drifting towards zero when running for half an hour. Do you need to have a film on the whole surface of the crystal?

>>16025352
I'm starting to recognize your posts as well.

>>16030187
A fool's words

>>16030414
>>16030076
smartest nofap poster

>>16028116
Proof: this is trivial

Can eugenics solve cancer?

>>16030529
only if you somehow eugenic people into being immune to radiation

>>16030497
That reads like it's AI-generated.

>>16030555
That's what I thought.

>>16016265
85 to 115 is Mid Wit. At 128 you are in the smarter than your average Pleb category. "Genius," is probably 141 and higher.

>>16016355
It's the unemployed part that will hold you back. Loads of normal working men have wives that are teachers. Actual "kept men," are miserable. You absolutely want a job if you are a man and going to marry richer and or smarter. If she has even half a brain, she isn't going to put up with you being a man child doing nothing but chores and entertainment.

>>16016630
Wrong question. The right question is how good are you at Differential Equations, proofs, etc.? A lot of IQ tests measure vocabulary and math more than anything else. Or if you are doing the puzzle game version, how well have you studied and memorized your puzzles?

Any /mid/bros ITT? What brings you to /sci/? For me, I’m just trying my best at school and at learning in my free time. I know I’m not super clever but slowly being able to understand more things makes me happy.

>>16030888
The quest for knowledge is its own reward. Life is about doing things that make you happy.

>>16015839
Why do /sqt/ posters have no wisdom or intelligence whatsoever on combinatorial math? You're all of a bunch of undergrad frauds

>>16030922
>/stupid question thread/
Yes anon, the clue is in the general name. Most posters are undergrads or not even that. Getting mad at them for trying to learn makes you the fool.

>>16030983
If the bees who post the honeypot don't make honey, there's nothing sweet about it.

>>16031003
Bee's don't waste their time explaining to flies that honey is better than shit.

Can someone explain why only 4 is solution?
Because I also get a 2 but the book tells me the only solution is 4 but it isnt clear about the "why"

>>16031118
>[math]3 + 2 = 3(2) - 5[/math]
>[math] 5 = 6 - 5[/math]
>[math] 5 = 1[/math]

????????

>>16031118
how would 2 be a solution to this?

>>16031126
>>16031128

>>16031118
Do the case work

>>16031138
[math]3x-8<0[/math] doesn't solve the question, Michael.

>>16031135
>>16031138
doesn't matter what fancy tricks you pull if the answer doesn't fit into the original equation.

>>16031118
[math]3x - |x| = 8 \\
\text{if } x \gt 0 \text{ then } 3x - |x| = 3x - x = 2x = 8 \implies x = 4 \\
\text{if } x \lt 0 \text{ then } 3x - |x| = -3|x| - |x| = -4|x| = 8 \implies |x| = -2, \text{ so no solution }
[/math]

>>16031138
If 3x-8 is in the image of |x|, it can't be less than 0...

>>16031138
Thank you!!

>>16031138
You can't hide your grievous error from the internet. It's here forever.

>>16031142
Had to delete my work because I accidently doxxed myself lol but could you explain why I was wrong?

Isnt this right? It shows 2 aint the solution because 2<0 is wrong

>>16031154
Nvm I see it, it's because absolute value can't be negative so one of my cases can be thrown out

>>16031156
Forgot pic

Btw
>>16031162
Good math, great teacher
>>16031126
>>16031128
Shit math, shit teacher
>>16031145
>>16031142
>>16031144
Good math, shit teacher

>>16031164
>shit math
my guy, that was your own claim

>>16031154
>>16031156
I see what you mean now, and I guess it works, but it's a very backwards way of showing 2 isn't a solution when you can just plug it into the equation to check.
It looks like you're solving for x in both cases with no regard for which one is reasonable.

>>16031164
> Good math, great teacher
But it's wrong. The only correct answer is >>16031145

>>16031172
Why is it wrong? It clearly show why 2 isnt a solution
Dont just tell me its wrong, tell me why
Btw the 8 is negative, your shit doesnt do anything other than confuse me
You cant just throw a bunch of signs at me and expect me to understand the WHY

>>16031194
> You cant just throw a bunch of signs at me
You mean the symbols? If you don't understand those how the fuck are you expecting to answer this kind of question?

>>16031200
I understand but its wrong, you fucked up the symbols and I dont understand what is what or why.
Stop posting please, you dont know how to teach
Thank you anyways

>>16031200
he's not looking to understand meaning of the symbols
just step-by-step guides of "if you see this, do this" with no understanding as to why he's doing them

>>16031218
I just got it, found a video on jewtube, you simply replace the 2 on the original ecuation

>>16031095
What does that have to do with combinatorics?

>>16031221
you should try to understand absolute value better, that is if you give a fuck at all about understanding the problem

>>16031218
Ahh, that would explain his attitude. I can't see him getting very far.

Something that probably isn't very complicated but is throwing me off in Physics is the sign for r when solving electric field vector problems.
So the red represents a negative charge and the blue a positive, I do understand that a positive charge points away, and a negative charge points towards itself. What I am not getting is how the r sign is represented in the electric field equation. For example, if the component is pointing towards Q1, because it is negative, does that mean the r is a negative sign? And the Q2, because it is pointing away from itself and going upwards, is it positive?
Secondarily I wanted to ask if the distance squared in this type of problem is always positive.

What are the fields of electrical engineering that deal the least with electronics? Either digital or analog electronics, I don't want to work with that crap

I have scoliosis, asthma, atopic dermatitis, multiple allergies and crackling in my ears. I also have involuntary tremors 2-3 times a day.
What is my underlying disease?

>>16031445
An inability to go see a doctor.

>>16031452
I will die anyway.

>>16027890
>>16027891
bump

How do I factor/reduce this

>>16031552
Into this...

>>16031552
Multiply the numerator and denominator by x^2

>>16031556
Then what?

>>16031554
>>16031552
Anyone?

>>16031608
[math] \displaystyle
\frac{x^2 + x}{x^2-1} = \frac{x(x + 1)}{(x+1)(x-1)}
[/math]

>>16031634
How do I multiply
1-1/x^2 by x^2?

>>16031655
okay, maybe dont ask "then what?" if you had trouble with the initial instructions
[math] \displaystyle
a(b+c) = a \cdot b + a \cdot c \\
x^2 (1 - \frac{1}{x^2} ) = x^2 \cdot 1 - x^2 \cdot \frac{1}{x^2} = x^2 - \frac{x^2}{x^2} = x^2 - 1
[/math]

does a research project on neuroplasticity in Parkinson's sounds like it would be a good idea for my thesis? I'm trying to pick from the list and it sounds somewhat fun but i imagine there's some huge difficulty that will arise that i haven't thought about

>>16031657
>>16031556
What is called? To add a random/new number to multiply and change everything

>>16031668
What is this called*. Or why/when can I use it

>>16031668
theres not really a name for it, its just multiplying. we chose x^2 here because we knew it would get rid of the denominator in the bottom, which is a good place to start when youre trying to reduce things.

>>16031668
Simplification.

Am I stupid for thinking a black hole isn't that complicated? The "interior" of it is just a hyper-dense sphere of all the shit that has been pulled past the event horizon. The only reason it's mysterious is because we can't see that sphere and gravity affects the perception of time.

>>16031712
Well they can be the brightest objects in the universe, they seem to be needed for galaxy formation, we have no physics to describe that "super dense matter", we don't even know what form it would take, and all the information about what enters the black hole seems to be lost breaking a fundamental law of physics. So yeah, not that mysterious or complicated.

Let [math]T: \mathbb{R}^n \to \mathbb{R}^n[/math] be an invertible map which preserves Lebesgue measure and commutes with positive scalars (i.e. [math]T(cx) = cT(x)[/math] for all [math]c > 0[/math] and [math]x \in \mathbb{R}^n[/math]).

Is [math]T[/math] a linear map?

Let [math]V[/math] be a complex inner product space, and let [math]f \in \operatorname{End}(V)[/math]. We denote [math]\mathfrak{R}(f)=\frac{f+f^{*}}{2}[/math] and [math]\mathfrak{I}(f)=\frac{f-f^{*}}{2i}[/math].

a) Prove that [math]\mathfrak{R}(f)[/math] and [math]\mathfrak{I}(f)[/math] are self-adjoint operators and that [math]f=\mathfrak{R}(f)+i \mathfrak{I}(f)[/math].

b) Prove that [math]f \circ f^{*}=f^{*} \circ f[/math] if and only if [math]\mathfrak{R}(f) \circ \mathfrak{I}(f)=\mathfrak{I}(f) \circ \mathfrak{R}(f)[/math]. In this case, we say that [math]f[/math] is normal.

I'm stuck in the part b. Can I show it proving that [math]\mathfrak{R}(f)\mathfrak{I}(f)=\mathfrak{I}(f)\mathfrak{R}(f)[/math]?
I mean, to show that [math] \frac{(f+f^*)}{2} \frac{ (f-f^*)}{2i} =\frac{( f-f^*)}{2i}\frac {(f+f^*)}{2} [/math]
I'm super retarded when it comes to compositions.

How did red turned to yellow?

>>16019466
it all depends on the filter basis the limit is defined on. if you've got the limit n5, then it makes sense since log and the identity function are both continuous at 5, for ninfty, not so much

>>16032062
What bothers you about composition?
If you have two maps, [math]f[/math] and [math]g[/math], their composition `looks like' [math](f \circ g)(x) = f(g(x))=fgx[/math].
Maybe it's clearer to you if you try to show that [math]\frac{( f-f^*)}{2i}(\frac {(f+f^*)}{2}(x))=(\frac {(f+f^*)}{2}(\frac{( f-f^*)}{2i}(x))[/math] for any [math]x[/math]?
You shouldn't need anything more than linearity.

>>16019466
>>16032614
mean to write [math]n\to 5[\math], [math]n\to \infty[\math]

Let [math]R[/math] be a unitary ring, [math]M[/math] an [math]R[/math]-module and [math]R^{\otimes A}[/math] be the free module over some set [math]A[/math]. The lecture notes I'm reading state "Specifying a map [math]R^{\otimes A}\to M[/math] is equivalent to specifying a map [math]R\to M[/math] for each [math]a\in A[/math]". What I'm confused about is how to prove that given that linear independence and bases of modules haven't even been introduced yet.

>>16032607
given that [math]1\neq x\neq -1[/math] we have [math]1=\frac{x-1}{x-1}=\frac{x+1}{x+1}[/math], hence: [math]\frac{1}{2(x-1)} = \frac{1}{2(x-1)}\cdot 1 = \frac{1}{2(x-1)}\cdot \frac{x+1}{x+1}[/math] and so forth.

>>16025594
trying to learn physics without having mastered the underlying math is retarded imo. Read some introductory analysis and linear algebra books first, like amann escher

>>16020835
maimon was right about you retards

>>16031668
its called introducing shit into your expression to make it more pretty like. also known as algebra