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Riddle your diddle by Archie Nemmerhock - Tue, 05 Apr 2016 18:49:37 EST ID:cTPi6AuQ
File: 1459896577222.gif -(2565092B / 2.45MB, 300x226) Thumbnail displayed, click image for full size.
There's two guys:
If guy #1 borrows 2 dollars from guy #2, they have the same amount.
If guy #2 borrows 2 dollars from guy #1. he has twice the amount of guy #1.
How much money do they have from the start?
1 posts and 1 images omitted. Click Reply to view.
 >> Phoebe Brookwater - Sat, 09 Apr 2016 19:05:24 EST ID:cTPi6AuQ Ignore Report Quick Reply >>15084Yes, I am actually 12 years old and currently attending middle school. I thought this thread would be super stoked on me and all like "wooow, I can't figure it out. Wooow, dude, what is this? wooow"Fuck all y'all nb User was banned for this post User was banned by: Lekta Reason: See you in 6 years.
 >> Whitey Socklesick - Sun, 10 Apr 2016 15:05:44 EST ID:mUpp8lCW Ignore Report Quick Reply >>15083To actually solve by showing workx = guy 1y = guy 2Statement 1(*) x + 2 = y - 2(x borrows 2, so he has +2, y lends 2 so he is -2)Statement 22*(x-2) = y + 2so...(**)2x - 4 = y + 2 Comment too long. Click here to view the full text.
 >> Phyllis Nivingshit - Mon, 11 Apr 2016 07:47:21 EST ID:A2j/BW/W Ignore Report Quick Reply 1460375241260.gif -(2532232B / 2.41MB, 452x256) Thumbnail displayed, click image for full size. >>15086Wow! Such math! So amaze! Wow!
 >> Phineas Condlenore - Sat, 07 May 2016 17:02:14 EST ID:3U6ZTH6i Ignore Report Quick Reply >>15086Sooo.....Lekta thought Phoebe was serious...Lekta should be a cop.
 >> Priscilla Pinkinstone - Sat, 16 Jul 2016 01:31:09 EST ID:Tg2WbKCI Ignore Report Quick Reply >>15086poor guy skipped reading comprehension class, wait that isn't real, you should still feel bad

Gamedev is great by Ian Dundleludging - Wed, 04 May 2016 00:31:32 EST ID:7yI2oiC+
File: 1462336292491.jpg -(194802B / 190.24KB, 906x906) Thumbnail displayed, click image for full size.
it's a great way to see the impact of changes in your model. Of course this applies mostly to folks interested in applied mathematics. But what is "pure" mathematics, but math that hasn't been yet applied? Give me a physical interpretation of the fractional calculus. Better yet, show me it in a Game.

There's also the fact that a lot of gamedevs struggle with some basic maths, mostly stuff regarding linalg, quaternions come up a lot. You could probably help!

Did you know: There's a 420chan amateur gamedev community, >>>/vg/664016

And from a pedagogical pov, who'd bet against gamedev working its way into the classroom? It's the perfect confluence of any applied area you can think of, Fourier series to taxicab metric
 >> Clara Fadgebit - Fri, 20 May 2016 17:24:26 EST ID:WHIrmu8h Ignore Report Quick Reply 1463779466259.jpg -(153794B / 150.19KB, 610x261) Thumbnail displayed, click image for full size. > gamedev in the classroomIt would take the fun out of it eventually if it's forced. My first program was a game and later gamedev had me apply trig. It is still a lot of boring work, too, a lot of pure programming, so to speak, as pure maths is applied to maths.Planning is required when fleshing out an game from scratch. There could be too much freedom in a project to grade it. Gamification works better if fit to the audience, eg. in a logic puzzle game.
 >> Ian Goodworth - Sat, 11 Jun 2016 17:23:59 EST ID:+Gs8DK3Y Ignore Report Quick Reply >>15127True, making games is lots of programming and boring work until you get the interesting math part.I think programming shaders is a better way of teaching maths https://www.youtube.com/watch?v=0ifChJ0nJfMAnd to be honest most maths you will do in gamedev has to do with graphics.
 >> Shitting Crimmerfield - Mon, 20 Jun 2016 01:47:59 EST ID:ZiObD4pn Ignore Report Quick Reply >>15159Maybe gamedev isn't that good for applying maths, but I'm pretty sure it's good for making physics simulations.

How do I recover the signs of integrals and derivatives? by Nell Penderfedging - Sun, 15 May 2016 20:44:52 EST ID:1eeqYqTy
File: 1463359492478.png -(46691B / 45.60KB, 787x421) Thumbnail displayed, click image for full size.
I can define derivatives and integrals in terms of the Lebesgue
measure but how do I recover signs?

$$\left. \left\lvert \frac{\mathrm{d} y}{\mathrm{d} x} \right\rvert \right\rvert_{x = a}= \lim_{C \rightarrow \left\{a\right\}}\frac{\lambda^*\left( \left\{ y_x \, \vert \, x \in C \right\} \right)}{\lambda^*\left( C \right)}$$

$$\left\lvert \, \underset{\, \, x \in C}{\int} y \, \mathrm{d} x \right\rvert = \lambda^* \left( \left\{ \left( x , y_x \right) \, \vert \, x \in C \right\} \right)$$
 >> Martha Pudgestedging - Tue, 14 Jun 2016 12:22:55 EST ID:c7Q4EFJt Ignore Report Quick Reply So there's two ways to do this. The first is to define the integral in terms of the lebesgue measure and use the doublet distribution to define the derivative in terms of an integral transform and the second is to define a delta as the lebesgue measure of the increasing sections of a function minus the measure of the decreasing sections of a function and then define the derivative using the delta as normal.

Mathemusings by Betsy Puffingspear - Wed, 08 Jun 2016 18:56:24 EST ID:3U6ZTH6i
File: 1465426584120.gif -(333697B / 325.88KB, 256x256) Thumbnail displayed, click image for full size.
Hey, I thought this board would appreciate this question the most.

So you lightly press your fingers on a string to play the harmonic.
(I'm gonna pretend i have a c-string on my guitar because all the tables you will find lists c as the root note).

Lets say you play the 5th harmonic, lightly press 1/5 of the way from one end.
You hear an E, the 5/4 interval to C
The 3rd harmonic, a G, the 3/2 interval

This could lead me to believe that if I play the 7th harmonic,
I would get the 7/6 interval, somewhere between D and D#

But I what i hear is something slightly lower than A# (or Bb if you will)

I'm thinking it's because 6 is not a square number.
Comment too long. Click here to view the full text.
 >> Hugh Sessledock - Thu, 09 Jun 2016 03:14:56 EST ID:lYjTKStM Ignore Report Quick Reply 99% of modern instruments are tuned to equal temperament.That means each half-tone is separated by adjacent ones by a ratio of 2^(1/12).This also means that every interval (besides whole octaves) to an irrational number.So when you go up/down musical intervals you end up precisely where you started if the number of steps up/down are the same. This however means through that notes will sound slightly off to natural notes.I don't know if that answers you question:https://en.wikipedia.org/wiki/Circle_of_fifths#Circle_closure_in_non-equal_tuning_systems
 >> Clara Grimridge - Thu, 09 Jun 2016 06:33:41 EST ID:3U6ZTH6i Ignore Report Quick Reply 1465468421138.jpg -(25519B / 24.92KB, 1304x617) Thumbnail displayed, click image for full size. >>15154Well aware of the equal temperament thing.I also know that the 1/7 harmonic is not used in most Just Intonation tunings.I'm talking about the actual harmonic to interval relation.I kinda expected the 7/6 interval, 7 being the root note (the whole string) and 6 being the note I hear from pinching that whole string 1/7 of the way from the end.(6/7 of the way from the other end ofc)What I hear is closer to a 16/9 interval (I think it's slightly lower)I'm pretty sure it's because six times a seventh does not produce an octave of a seventh, like a square number would.Still I am unable to form a good theory of what's happening.
 >> James Trotman - Tue, 14 Jun 2016 16:46:24 EST ID:3U6ZTH6i Ignore Report Quick Reply 1465937184594.jpg -(13970B / 13.64KB, 394x467) Thumbnail displayed, click image for full size. Well if anyone cares, I figured it out to my satisfaction.4 being the closest square number; 4 sevenths of the string, bringing out the 7/4 interval of C, the flat Bb; is the one ringing out the most when I pinch a seventh.Was pretty obvious in hindsight. nb.

Generating Polynomial by Cedric Mavingwell - Fri, 03 Jun 2016 05:39:35 EST ID:FvfJV3ZM
File: 1464946775420.png -(17720B / 17.30KB, 682x185) Thumbnail displayed, click image for full size.
Can anyone shed some light? I thought I just had to substitute powers of t into this equation to get the answer. Am I missing something stupidly obvious? I just can't get to the first line of the answer. http://imgur.com/a/9iWQ1
 >> Hannah Gattingmot - Fri, 03 Jun 2016 11:53:21 EST ID:A2j/BW/W Ignore Report Quick Reply You have to use Taylor expansions. So the first step is to substitute the Taylor expansion for the exponential function. Then you substitute the Taylor expansions for the different powers of the (1-t) terms. Then you group like powers of t. Whoever wrote the solution fucked up by squaring the t inside the parentheses in the third line btw, but they still got the correct result.
 >> Reuben Pittwill - Sat, 04 Jun 2016 04:44:18 EST ID:Ktnbl7MZ Ignore Report Quick Reply >>15147 Thank you mate.
 >> Phoebe Dimmerpuck - Sat, 04 Jun 2016 12:19:38 EST ID:A2j/BW/W Ignore Report Quick Reply >>15148No prob.

Probability by Jack Bloffinghood - Sun, 29 May 2016 19:59:52 EST ID:lgvPZ+E8
File: 1464566392861.jpg -(94901B / 92.68KB, 650x434) Thumbnail displayed, click image for full size.
How do you solve these types of problems:

Lets say you have a chicken who, on average, lays 1 egg per day.
After 7 days what is the probability that the chicken will have laid at least n eggs?
 >> Hannah Daffingway - Mon, 30 May 2016 11:31:43 EST ID:lYjTKStM Ignore Report Quick Reply You need to know which probability distribution and it's parameters.Most examples assume a normal distribution, but even then you need to know it's sigma value.Of course it would be interesting to solve the differential equation for al sigma values and number of eggs.
 >> Phyllis Soblingnedge - Mon, 30 May 2016 11:33:06 EST ID:A2j/BW/W Ignore Report Quick Reply https://en.wikipedia.org/wiki/Poisson_distribution
 >> Eliza Crabblewater - Mon, 30 May 2016 21:48:39 EST ID:lgvPZ+E8 Ignore Report Quick Reply 1464659319762.gif -(4642823B / 4.43MB, 500x500) Thumbnail displayed, click image for full size. >>15141>>15142ThanksI did the calculations using a Poisson distribution and it seems to be working great. The actual average is nice and close the expected average whether I set lambda to 5 or 5000.pic related

Help explain Principal Component Analysis to a dummy by Oliver Lighthall - Tue, 10 May 2016 12:55:53 EST ID:xd9SEzRh
File: 1462899353126.gif -(21904B / 21.39KB, 505x369) Thumbnail displayed, click image for full size.
Hey guys,

I don't know anything about Principal Component Analysis (PCA) but I'd like to learn. Can someone explain to me the PCA algorithm (the algorithm to find the set of PCA vectors) for operating on a 2D set of real data?

Here's my understanding of it so far (feel free to add corrections):
• First you have to normalize your set of real datapoints because PCA works best on normalized datapoints
• Then, calculate the mean of the data-set (this is just the flat-average of the various components of the data). So in R2 for instance, this is (x1 + x2 + x3 +...) / (n) and (y1 + y2 + y3 + ...) / (n) for finding the mean X-value and mean Y-value.
• Next, subtract the mean from the data-points. This centers the data around the origin.
• Then we begin calculating the variance-covariance matrix, which we're going to use as part of the PCA algorithm
• Variance of each datapoint is calculated as the "average squared deviation from the mean" which is in this case (the case of already having subtracted the mean from each datapoint) we can simply square each datapoint, then divide by the number of datapoints to find its variance (is this even correct?)
• Then you have to calculate the covariance (I'm really fuzzy on how to do this part given our initial dataset).
• Next step is to assemble the variances and covariances that we have calculated into the variance-covariance matrix
• Then you calculate the eigenvectors and eigenvalues of the variance-covariance matrix. There should be one eigenvector (and each eigenvelue corresponds to one eigenvector) for each dimension in the original dataset (so for 3 dimensional data, you should get 3 eigenvectors).
• Then for PCA, you sort the eigenvectors by their eigenvalues to find the principal components. The principal components' vectors are the eigenvectors we calculated in the previous step.

Is this right? Can someone explain this to me more simply?

Fuck squares by Isaac Newton - Sat, 07 May 2016 01:20:21 EST ID:HaG6KVm7
File: 1462598421690.png -(847B / 847bytes, 225x225) Thumbnail displayed, click image for full size.
I fucking hate squares and shit.

That's why I made apples into circles, they use to be fucking square.

Can Math Ban Me? Fucking squares suck. Soon I will amke sure you can only have round shit. I tried to impress a bitch with a fucking square once, wanna know what the fuck happened? She fucking cried! Cried so loud, even saying, "A trapezoid would have been better!" The nerve of that bitch.

The nerve of /math/. Someone here PROMISED that the bitch would let me stick my shit in her if I gave her a square. You owe me a fixed marriage./ Send nudes of your daughter, I call it even.
 >> George Banderwater - Sat, 07 May 2016 05:04:23 EST ID:A2j/BW/W Ignore Report Quick Reply 1462611863500.jpg -(440782B / 430.45KB, 960x540) Thumbnail displayed, click image for full size. You're a square!

What type of math are you studying? by Isabella Habblefield - Sun, 14 Feb 2016 19:31:46 EST ID:Dk8yywxc
File: 1455496306932.jpg -(396464B / 387.17KB, 2480x3508) Thumbnail displayed, click image for full size.
Right now I'm studying large cardinals in set theory and trying to learn more about algebraic topology. A good place to start with topology is the "Topology" by Munkres, and if you have a strong set-theoretic back ground I recommend "The Higher Infinite" by Kanamori for learning about large cardinals. The fact that the existence of a large enough number can be equivalent to something that has nothing to do with cardinals at face value still fascinates me. Here's an interesting chart that shows how we can assume the existence of large enough cardinals right up to contradiction.

What parts of math are you interested in or studying? Why? What are some resources that you recommend for others to get into it?
 >> Molly Blablingtack - Sun, 13 Mar 2016 21:01:06 EST ID:Ayxv8mCh Ignore Report Quick Reply I like to study abelian functions and other things related to Riemann surfaces. I like the complexity (no pun intended) of the material and Riemann surfaces is at the intersection of many interesting fields. It is often an experimental ground for alg top, alg geom, diff geom, etc etc. Anyone interested should first learn about complex variables from churchill and brown and then move onto algebraic curves and riemann surfaces by rick miranda.
 >> Hugh Drubberforth - Thu, 31 Mar 2016 20:52:08 EST ID:fIwfJdEz Ignore Report Quick Reply I'm working through abstract algebra. I've got an engineering degree, but the math we learn there is much more pragmatic, model-oriented, and number-focused. Whereas math like this, in and of itself, is a bit like a model. For example I personally conceptualize mappings as a sort of data-typing, that's just where it rests in my mind, but I know that it is a more general concept than that-- allowing quotient sets and such has sort of blown my mind in this regard.I'm trying desperately to cling on to Allan Clark's Abstract Algebra book, which I've been told is really not for beginners. I can see that, but I can fill in the gaps with stuff on the internet. I spend a lot more time puzzling about this book than with other intro texts. Fiddling with the numbers, and trying hard to convince myself of things, and solve problems with my own reasoning, instead of regurgitating the examples. It's pretty fuckin' rough so far, especially since the only work I have with formal logic/sets is a brief introduction in engineering statistics, and in "severely boiled the fuck down" discrete math 301. And that was about 10 years ago, so yeah. But I'm trying, and I can usually understand the proofs others arrive at, if not nearly arrive at them myself. I'm probably wasting my time, but I like the puzzles.
 >> Hannah Dinningtitch - Sat, 09 Apr 2016 18:19:26 EST ID:LR+0MgV1 Ignore Report Quick Reply 1460240366149.png -(258528B / 252.47KB, 1920x1080) Thumbnail displayed, click image for full size. >>15046I like to study computational theory, so things like lambda calculus and functional programming langues. It's a really nice mix between pure mathematics and computer science.
 >> Hannah Sollernodge - Fri, 22 Apr 2016 12:45:25 EST ID:WD6PkLOh Ignore Report Quick Reply Well I studied Pharmacology, but I've been re-reading some of my Advanced Higher (stuff you do in the last year of secondary education) maths and reading a couple of books aimed at the average person. Are there any college-level maths topics which are particularly cool or satisfying? I loved that feeling of it all coming together when I relearned partial fractions, proofs, calculus (before you get trig functions involved and it all goes to shit). Anything in the same vein I could learn now? I have no problem putting in hours of work, and I usually don't have a problem grasping new mathematical concepts

i can't do math by Lillian Saffingbanks - Fri, 15 Apr 2016 18:21:07 EST ID:YoFLr1Ak
File: 1460758867923.jpg -(272402B / 266.02KB, 1300x924) Thumbnail displayed, click image for full size.
im 25 and i can barely understand algebra, im a high school drop out.

what am i going to do i need to go back to college but if i don't pass their math test i am not allowed in....what shall i do?
 >> Walter Murddock - Fri, 15 Apr 2016 19:06:10 EST ID:A2j/BW/W Ignore Report Quick Reply https://www.khanacademy.org/math/You can try teaching yourself math using the above link or hire a tutor.
 >> Samuel Drimbletedging - Wed, 20 Apr 2016 22:12:08 EST ID:RHLOntyV Ignore Report Quick Reply If you're going to community college you should be fine, many have pre-algebra remedial classes you can take.
 >> Hannah Sollernodge - Fri, 22 Apr 2016 12:37:03 EST ID:WD6PkLOh Ignore Report Quick Reply >>15093I recommend Khan academy very highly. I'm an amateur but I really love maths, and I love to share it with my girlfriend (who never did well at school), but sometimes we just get stuck on something and I've explained it every way I can to her.Without fail, we watch the KA video and she understands in 5 minutes

PDEs by Jenny Cabblehall - Fri, 15 Apr 2016 11:45:52 EST ID:FXvLlomd
File: 1460735152003.png -(363794B / 355.27KB, 1920x1080) Thumbnail displayed, click image for full size.
guys help

Why are we assuming h(x, t) to be a fourier sine series instead of using the whole fourier series? It's certainly easier for decomposing the equation into an ordinary differential equation but what if it can't be represented by sine alone?

Also, why do we assume that the function in the integral from 0 to L of h(x, t)*sin(n*pi*x/L)dx is an even function? If it's an odd function, then the integral converges to zero and then what do you do?
 >> Jenny Cabblehall - Fri, 15 Apr 2016 16:19:42 EST ID:FXvLlomd Ignore Report Quick Reply Ok so i understand now why h(x,,t) is a fourier sine series, but it seems like this method only works for when h(x,t)'s x part is an odd function, otherwise the integral either becomes zero or the function has a sine AND cosine series representation. If this is the case, this method doesn't work, right?

I don't believe in Math by A Wizard - Thu, 07 Jan 2016 00:39:32 EST ID:+mzdzIig
File: 1452145172589.jpg -(8086B / 7.90KB, 252x200) Thumbnail displayed, click image for full size.
how come you can't put any symbol in any order and make the claim that it is what you say it is?

>its a conspiracy
3 posts omitted. Click Reply to view.
 >> Isabella Nangerhudge - Fri, 12 Feb 2016 02:06:21 EST ID:ac89ToyY Ignore Report Quick Reply T: OP --> Me is not linear
 >> Barnaby Dunderlat - Sun, 14 Feb 2016 02:50:29 EST ID:aLV1scJv Ignore Report Quick Reply I think you're misconstruing the concept of digits with the concept of numbers. Like, there's the number 5 and then there's the digit 5. Numbers represent a number of things. 5 is a number; 5478 is another number. Numbers are also abstract concepts, and to write them down we use digits. Digits are just symbols used to communicate a number in writing; the same way that letters are the symbols we use to write words. Basically all the math you learn and see can be put into two categories: actual math, based on intrinsic properties; and results that are byproducts of the way we happen to put pens on to paper.Take for example something like the 37 trick. Pick any digit and write it down three times. So, something like 555. Add those three digits together: 5+5+5=15. Divide your original three digit number by the sum of its digits. Regardless of the digit you start with, you'll always get 37.But if you think about what >>15017 talks about regarding different civilizations you can think about how an ancient Roman would do this. Like, if a roman used the digit V, the trick wouldn't give 37. The trick is actually a combination of the fundamental properties of math that don't change when they're written in different ways and a quirk of our current system.111 is divisible by 5 regardless of how you write the figures down. CXI is divisible by III. 一百十一 is divisible by 三, etc. You're always going to get 37, regardless of what symbols you're using. If you don't believe me, go get 111 of something. You'll always be able to split them into 3 piles of 37. The property is detached from any one expression of the numbers. Comment too long. Click here to view the full text.
 >> Molly Clayfield - Wed, 09 Mar 2016 02:29:30 EST ID:FwRHmRUr Ignore Report Quick Reply god invented math to troll you fucks, checkmate
 >> Molly Grandhood - Fri, 01 Apr 2016 12:42:21 EST ID:pPznVtZ8 Ignore Report Quick Reply 1459528941946.jpg -(48015B / 46.89KB, 720x540) Thumbnail displayed, click image for full size. >>15015you canit's called SSDoCt0rTo
 >> Albert Fonderchork - Sun, 10 Apr 2016 14:19:31 EST ID:BI41XwUF Ignore Report Quick Reply 1460312371052.jpg -(59771B / 58.37KB, 600x799) Thumbnail displayed, click image for full size. Apart from the most elementary mathematics, like arithmetic or high school algebra, the symbols, formulas and words of mathematics have no meaning at all. The entire structure of pure mathematics is a monstrous swindle, simply a game, a reckless prank. You may well ask: "Are there no renegades to reveal the truth?" Yes, of course. But the facts are so incredible that no one takes them seriously. So the secret is in no danger.

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