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420chan is Getting Overhauled - Changelog/Bug Report/Request Thread (Updated June 12 [TaimaTV Update])
mathematics?!?! Ignore Report View Thread Reply
billyjoel - Tue, 13 Jan 2015 00:40:58 EST ID:29R5cpQe No.14559
File: 1421127658769.jpg -(799991B / 781.24KB, 2000x2597) Thumbnail displayed, click image for full size. 799991
WHAT IS DIFFERENTIAL EQUATIONS ALL ABOUT?
1 posts and 1 images omitted. Click View Thread to read.
>>
Molly Blerringsore - Mon, 19 Jan 2015 02:38:13 EST ID:7MP0s8P6 No.14569 Ignore Report Reply
weird ass equations that relate a value and the value's own rate of change.
>>
Nigger Dubberdet - Fri, 23 Jan 2015 15:02:12 EST ID:OlFjx/Q0 No.14572 Ignore Report Reply
It's a functional equation in which there are differentials.

A functional equation is an equation, in which the unknowns are functions, instead of numbers like in algebraic equations.
Solving an algebraic equation means finding a number (numbers) that satisfy given algebraic equation.
Solving a functional equation means finding a function (functions) that satisfy given functional equation.

Generally functional equations are very hard to solve. There is no general solution to such equations. Subset of those equations, differential equations, are particularly useful, and thus intensively researched. There are general ways to solve some rather simple classes of DE, but not all of them (like the infamous Navier-Stokes equations)
>>
Phoebe Genderstitch - Fri, 23 Jan 2015 17:07:04 EST ID:E00AZouD No.14574 Ignore Report Reply
Sometimes when you have a problem, you can describe it using an algebraic equation and this will give you at least one numerical value to answer your problem. It should allow you to at least narrow down your solution-search to a certain type of number.
Other times when you have a problem, you can describe it using a differential equation and this will give you at least one type of relationship between numerical values (aka functions) that will allow you to answer your problem. It should allow you to at least narrow down your solution-search to a certain type of characteristic relationship (function).

Some problems are simple and the solution will be a number. Other problems are more complex and the solution is a whole bunch of numbers that all share a certain relationship with one another.


Number one Ignore Report View Thread Reply
David Barddale - Thu, 23 Oct 2014 18:57:56 EST ID:lnIBho4U No.14435
File: 1414105076933.gif -(187803B / 183.40KB, 650x510) Thumbnail displayed, click image for full size. 187803
1 is weird man.

If the basis for the value of one is wrong, all of math is pretty much fucked up right?

Also I wonder how aliens count things. Like, would they look at our system of counting things and be like wtf why is this so overcomplicated.
5 posts and 2 images omitted. Click View Thread to read.
>>
Rebecca Poshhall - Sun, 18 Jan 2015 00:50:52 EST ID:6XbVXz0U No.14566 Ignore Report Reply
>>14545
I read some of Russel's writing on the subject and I still have a hard time wrapping my head around the concept that numbers themselves are sets (or classes, as he calls them).
>>
Jarvis Hummerbick - Sun, 18 Jan 2015 10:34:32 EST ID:IYIYaVNy No.14567 Ignore Report Reply
>>14566
THink of them like segments on the number line. You can have a segment going from 0 to 1. THat's 1, and it contains the 0 (empty) set. A segment going from 0 to 2 contains 0, 1 and 2, and so on. A segment that does not include 0 wouldn't exist in this system.
>>
Molly Blerringsore - Mon, 19 Jan 2015 02:36:01 EST ID:7MP0s8P6 No.14568 Ignore Report Reply
I mean, like, one is just like an idea, man.


Average & Effective value Ignore Report View Thread Reply
Electro M. Echanics - Mon, 12 Jan 2015 07:37:40 EST ID:Y56yfAG4 No.14557
File: 1421066260968.jpg -(52819B / 51.58KB, 640x369) Thumbnail displayed, click image for full size. 52819
Somebody here who can calculate the average value and the effective (True RMS) value of this function?
I would be Very Thankful.
>>
Electro M. Echanics - Mon, 12 Jan 2015 07:41:40 EST ID:Y56yfAG4 No.14558 Ignore Report Reply
This might help: http://meettechniek.info/compendium/average-effective.html
>>
Electro M. Echanics - Wed, 14 Jan 2015 08:44:45 EST ID:Y56yfAG4 No.14563 Ignore Report Reply
Nvm. Already got it !


Math Problem Ignore Report View Thread Reply
Frederick Niggerhall - Wed, 10 Dec 2014 12:46:28 EST ID:J8biWsPj No.14509
File: 1418233588653.jpg -(49410B / 48.25KB, 527x640) Thumbnail displayed, click image for full size. 49410
Hi guys, I'm hoping I can get some math tips from you all. My girlfriend is a math major, and tells me that she's been having a lot of sex dreams about math recently. Sometimes, I'll find a calculator under the sheets. I'm not really a math person, so I'm not sure what to make of this or how to respond. Any tips? Thanks guys.
3 posts and 1 images omitted. Click View Thread to read.
>>
Lillian Nunderworth - Fri, 02 Jan 2015 00:24:58 EST ID:1f/Knshx No.14548 Ignore Report Reply
>>14538

I died at l'hospital.
>>
John Crisslekon - Wed, 07 Jan 2015 01:09:39 EST ID:oEhGbHUR No.14554 Ignore Report Reply
>>14538
Golden post. lim x → 10 x/10
>>
James Grandcocke - Sun, 11 Jan 2015 08:47:33 EST ID:oEhGbHUR No.14556 Ignore Report Reply
1420984053798.gif -(1148881B / 1.10MB, 300x300) Thumbnail displayed, click image for full size.
Here's my favorite math joke.

A Cauchy sequence is walking through town, when it sees on a wall a poster advertising a night club. "No limit night on Friday" it says. The sequence is all psyched for it, cause it's been a while since he last went clubbing, and this looked like the perfect occasion. So the sequence quickly goes back to it's place to put on it's best clothes and a nice cologne before heading to the club.
But then, when it is about to get in, the bouncer stops him and says :
Sorry, it's complete.

I just realised it may not work as well in English as it does in French. If it's the case and you're frustrated, here's a quickie.

Logarithm and Sinus wake up after a huge party. Sinus has the worst hangover ever, while Logarithm is fresh as a rose. Seeing the awful face his friend has, Logarithm says Man you really don't know your limits, don't you ?


Question about real numbers Ignore Report View Thread Reply
Doris Blimmerladge - Mon, 15 Dec 2014 11:40:37 EST ID:akf5zfsA No.14524
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Is there a function that can project the entire set of real numbers onto an arbitrarily sized interval within the real numbers?
4 posts and 1 images omitted. Click View Thread to read.
>>
Beatrice Wommergold - Tue, 16 Dec 2014 15:53:58 EST ID:uPru0qmD No.14533 Ignore Report Reply
>>14524
Hyperbolic tangent :
tanh(x)=(e^x-e^-x)/(e^x+e^-x) maps R->(-1,1)
atanh(x)=1/2 ln((1+x)/(1-x)) maps (-1,1)->R
a*tanh(x)+b maps R->(-a+b,a+b)
atanh((x-b)/a) maps (-a+b,a+b)->R

The nicest functions you're going to find
>>
Esther Fabberhall - Tue, 23 Dec 2014 20:47:35 EST ID:K8qJv5EF No.14542 Ignore Report Reply
>>14533
^This guy's post is correct if you're looking for continuous bijections. If you're looking for just a continuous map from the reals to [a,b], you can just choose f(x) = [(b-a)/2]sin(x) + (b+a)/2
>>
Thomas Bangerham - Fri, 26 Dec 2014 18:20:04 EST ID:SlKfpVpP No.14546 Ignore Report Reply
>>14524
another interesting question is whether you can project an arbitrarily sized interval within the real numbers onto the set of real numbers

answer is yes

also you can map a line of length 1 onto a cube of volume 1 etc.


Majoring in Math Ignore Report View Thread Reply
Cornelius Sollerwone - Tue, 02 Sep 2014 22:17:23 EST ID:kQQi+WA1 No.14343
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I want to know are good options for me career wise if I major in math. I just finished my first term and I don't really know what I'm doing. All I know is I enjoy math. The only thing I've had recommended to me is to become an engineer. I'm not great with electronics, computers, or mechanics. I think I could handle physics since that seems like just more applied math. I need college advice. I have a career advising appointment in a couple weeks but I would appreciate your advice!
2 posts and 1 images omitted. Click View Thread to read.
>>
Archie Worthingfield - Sun, 07 Sep 2014 18:17:12 EST ID:xvgqavvT No.14352 Ignore Report Reply
Functional programming. since you need to think like a mathematician to do it. Designing algorithms is another high demand job, especially in the finance/trading industry. Artificial Intelligence is all based of real analysis (proofs) so another field you can go into. Any stats job for the government like an environment agency, lot's of options.
>>
Cedric Hollertudge - Fri, 19 Dec 2014 05:04:22 EST ID:lx6v5XWF No.14540 Ignore Report Reply
Analytics and machine learning is in very high demand right now, and is where a large part of the field of CS in industry is heading, due to the big data problem.

These are very math heavy. I'd recommend getting into computational math.
Learn C. Learn Python. See if you can find some open source projects and make some contributions.

Programs can be very proof-like, in my own experience.
>>
Sophie Turveyhood - Fri, 19 Dec 2014 15:50:10 EST ID:4kDzPiCs No.14541 Ignore Report Reply
If you want a career in math you really have to get a PhD. That said, mathematician is regularly listed as one of the best, if not the best, job to have by many metrics. Grad school for math is always paid for. Schools will actually pay you a stipend to go there, even if you're not a top student.

Don't listen to people saying you can't get a job doing math. It has very high growth and almost no one wants to do it.


Maths tutoring Ignore Report View Thread Reply
Hugh Pupperford - Sun, 14 Dec 2014 17:18:22 EST ID:8T5tyzEs No.14523
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I wanna make some money on the side but by doing little work. I'm a maths undergrad so I was thinking of doing tutoring online. Anyone done this kind of thing before? How did you go about it? How much should I charge?
>>
Cedric Hollertudge - Fri, 19 Dec 2014 04:56:04 EST ID:lx6v5XWF No.14539 Ignore Report Reply
Your skill has probably taken years of work, so you should charge something above double minimum. I've charged $20 before, and $30 is not unreasonable.

I did my tutoring at a community college, and while I was a student, there were numerous tutors who weren't. You can see if any local CCs have openings.


can you help me? Ignore Report View Thread Reply
Phoebe Wankinwater - Wed, 17 Dec 2014 15:56:58 EST ID:K92q/1nw No.14537
File: 1418849818247.gif -(24799B / 24.22KB, 303x362) Thumbnail displayed, click image for full size. 24799
Hey guys, can anyone help with the following question? I am really stuck with it (and not through lack of trying, believe me)

A microphone has a polar pattern described as e = 1 + 1.5 * cos(angle).
Its on-axis sensitivity is given as -40dBV/Pa.
A sound source is such that it produces 75dB SPL at the microphone diaphragm.
What is the microphone output in miliVolts if the source angle is 90 degrees to the right of the microphone.

V(angle) / V(on axis) = (1+1.5 * cos(angle)) / (1+1.5 * cos(0))


haalp Ignore Report View Thread Reply
Angus Worthingshaw - Fri, 05 Dec 2014 16:44:51 EST ID:wdBv6x7g No.14503
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i need to find the area of the polar curve 2(a)sin(theta)

i keep getting 2(pi)(a)^2 but the book says its just (pi)(a)^2

i used the bounds 0 to 2pi which could be wrong but i dont see why.
1 posts omitted. Click View Thread to read.
>>
Nigel Depperham - Sat, 06 Dec 2014 00:41:32 EST ID:XpKKr8Wn No.14505 Ignore Report Reply
the fuck is (a) supposed to be? what are you integrating with respect to?
>>
Betsy Drocklekudging - Sat, 06 Dec 2014 23:47:00 EST ID:qz3c7Bt+ No.14506 Ignore Report Reply
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DICKS EVERYWHERE
>>
Phineas Mellyshit - Wed, 17 Dec 2014 04:30:13 EST ID:xatex5Q1 No.14536 Ignore Report Reply
The shape you are finding the area of is under the polar curve. You only integrate over the interval of theta that it takes the polar curve to draw the shape. After that its just tracing itself.


Is there an easy way to learn math? Ignore Report View Thread Reply
Simon Budgewick - Wed, 10 Dec 2014 18:07:16 EST ID:OMni8G61 No.14510
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23 year old male going back to college, here.

I will be attending college very soon, but the thing is, I struggle with mathematics, horribly. Even pre-algebra is an issue for me, sadly, and I really, really want to change this. My entire future depends upon it.

I don't know how to describe my issue with mathematics.. I try very hard to comprehend the concepts that escape me, but it's like no matter how hard I try and focus, I simply cannot grasp certain concepts.

Does /math/ have any easy learning tips, or any online resources to recommend me? Thank you very much in advance.
>>
James Sasslenot - Thu, 11 Dec 2014 06:53:18 EST ID:MTIV7/tU No.14514 Ignore Report Reply
>>14510
I never used it, but I often see it recommended here: https://www.khanacademy.org
Best of luck with your studies, have fun.
>>
Isabella Turveywell - Mon, 15 Dec 2014 15:49:46 EST ID:I7kVXtAY No.14527 Ignore Report Reply
Hi. I would suggest it, too.
Hopefully you will start next fall, or else it will be very futile.
That's why I want to drop out and try a trade and pay back my debts, learn enough and then get back.
How can something soo difficult be soooo desirable?
>>
Phineas Tootlock - Tue, 16 Dec 2014 13:19:18 EST ID:+c74Tbl7 No.14532 Ignore Report Reply
>>14510
Hey OP, I too struggled with math when I first started college, high school was a joke to me, I didn't take pre-calc, instead we had "accounting" which is a nice way of saying "basic math" lol. It was basic addition, subtraction, division, and multiplication and that was it. Needless to say math got fuckin hard when I got to college and physics was a bitch (uses a lot of math.) My best advice is to start at the beginning and work your way up. I didn't really understand the basics at first and that fucked me up in a few classes where the professor expected us to already understand the basics from high school classes. Khanacademy is an awesome site to learn on and youtube has a ton of videos that are useful (they'll show you how to work the problems step by step).


help? Ignore Report View Thread Reply
Cyril Doffingfield - Mon, 15 Dec 2014 14:21:23 EST ID:K92q/1nw No.14525
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hello friends,

not entirely sure if this is the right section but if anyone could offer an insight into these it was be greatly appreciated.

Thankyou.


Logic cw help Ignore Report View Thread Reply
Martha Trotwater - Thu, 11 Dec 2014 16:07:45 EST ID:FYItrjmk No.14517
File: 1418332065440.jpg -(33613B / 32.83KB, 420x319) Thumbnail displayed, click image for full size. 33613
Hey if anybody could take a look at this and give me the answers and or help me understand whats expected.
Suppose you are given an algorithm R that can test for any propositional
formula in Conjunctive Normal Form whether it has a resolution refutation or not.
(a) Describe (informally) how to construct from the algorithm R an algorithm T that can
test for any propositional formula in Disjunctive Normal Form whether it a tautology
or not.
(b) Demonstrate how your algorithm T works using the DNF
A ∨ (¬A ∧ B ∧ ¬C) ∨ (¬A ∧ ¬B ∧ ¬C) ∨ (¬A ∧ C)
(c) Explain how the computational complexities of the algorithms R and T related?


How to formalize this? Ignore Report View Thread Reply
Emma Secklebury - Sat, 25 Oct 2014 08:42:51 EST ID:8Yw0Br5B No.14438
File: 1414240971360.png -(27330B / 26.69KB, 280x345) Thumbnail displayed, click image for full size. 27330
How to mathematically formalize that the belief in God is absurd because there are infinitely many "supernatural" beings that can exist, and God is just one of them, and that THERE ARE INFINITELY MANY BEINGS WHICH EXCLUDE GOD'S EXISTENCE out of possibility. Ex: Out of invisible flying goblins, invisible pink unicorns, invisible demon alien reptiles, etc.
17 posts and 2 images omitted. Click View Thread to read.
>>
Fanny Snoddale - Thu, 11 Dec 2014 13:23:45 EST ID:dL8jDLUE No.14516 Ignore Report Reply
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>>14515
God is mathematics. Resurrecting itself through our application of it in technology.
NJ... Where art thou?
>>
Edwin Hattingworth - Wed, 03 Jun 2015 15:39:16 EST ID:4aRbvkOu No.14774 Ignore Report Reply
>>14507
Mathematics is built on Aristotelian first-order logic, using Zermelo-Fraenkel Set Theory (along with the Axiom of Choice). The axioms of mathematics are *chosen* so that the natural numbers (i.e. the counting numbers) can be constructed logically, step-by-step, and end up with all the usual properties we expect natural numbers to have. Yes, it is "all theory," but that theory is rooted heavily in elementary observations we make about quantity and measurement.

While there are a few mathematicians who look at other axioms for the basis of their mathematical system (dropping the axiom of choice, for instance), even these don't stray far from the general intuition we expect from counting. Don't even get me started on how COMPLETELY unrelated mathematics and metaphysics are: math is *not* number-wizardry.
>>
William Drenkingold - Thu, 01 Dec 2016 03:46:14 EST ID:I4oaqfW8 No.15282 Ignore Report Reply
Psssssssssst. Here's something I understood when I was 17.

> Infinite exclusive gods can be thought of
> => probability of one of them existing is an infinitesimal

> Infinite non-exclusive gods can be though of
> => probability of any such god existing is 50%

It's really not that hard, folks.
/thread


Theta Ignore Report View Thread Reply
Samuel Clissleridge - Thu, 11 Dec 2014 00:07:47 EST ID:zBSUDYOt No.14511
File: 1418274467054.png -(5718B / 5.58KB, 302x450) Thumbnail displayed, click image for full size. 5718
I'm currently trying to relearn some math skills that became a little blurry over the years so I can make the transition back into college a little bit easier, I'm using Khanacademy as my guide and I'm having trouble with trigonometry or with them?

So on the site I can't ever tell what angle I'm supposed to be solving for since there is no theta symbol. For example it gives me the following parameters: cos(<ABC) AC=12, BC=16, AB=20. I'll also make a diagram on MS paint showing exactly as the site does.

With the information listed above I'd assume theta would be at angle A because its Triangle ABC and not BAC, is my assumption correct? Can someone help me understand which angle I should use as my prospective so I can get the correct adjacent and opposites angles.
>>
Samuel Clissleridge - Thu, 11 Dec 2014 00:56:07 EST ID:zBSUDYOt No.14512 Ignore Report Reply
Yeah If a mod can just kill this post that'd be great I figured it out, plus it was asking for an angle and not triangle(misinterpreted the symbol) so that was part of the confusion, thanks.


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