## Search found 58 matches

Mon Sep 20, 2010 2:31 pm UTC
Forum: Mathematics
Topic: Linear ODEs
Replies: 7
Views: 1280

### Re: Linear ODEs

That depends what the 4 types in your course are...I may be being dense but I don't think I can split them into only 4 distinct categories - what are they? I'm guessing what you mean by homogenous ODEs are actually second order linear homogenous ODEs, in which case they aren't too bad, but I'm just ...
Mon Sep 20, 2010 12:18 pm UTC
Forum: Mathematics
Topic: Linear ODEs
Replies: 7
Views: 1280

### Re: Linear ODEs

Stick your c=1 in and then plug the function into the equation and verify for yourself that it works :) What you are doing is allowed, what you have done in essence is find a family of solutions to the equation - any c you picked in your function would work as a solution to the ODE - so in order to ...
Wed Sep 08, 2010 8:02 pm UTC
Forum: Fit Club
Topic: True Life: I eat because I'm bored.
Replies: 15
Views: 4241

### Re: True Life: I eat because I'm bored.

I should probably have disclaimered my massive, massive lack of common sense - that is a more sensible idea.
Mon Sep 06, 2010 8:06 pm UTC
Forum: Fit Club
Topic: True Life: I eat because I'm bored.
Replies: 15
Views: 4241

### Re: True Life: I eat because I'm bored.

I eat a lot because most of the time I'm pretty physically active, doing lots of sports etc. Whenever I've needed to cut down my eating due to a reduction in training or whatever, I've found myself also eating out of boredom etc, but I found some of the following things worked for me: Instead of eat...
Mon Sep 06, 2010 4:12 pm UTC
Forum: Fit Club
Topic: cycling
Replies: 199
Views: 153912

### Re: cycling

You will need to be quite fit, and have lots of time on the bike previous to accustom to the position, to be able to maintain that speed 6 hours a day for 7 days, plus be able to draft well and know how to ride in a group. Not entirely unattainable I'd imagine, but training for a 5k is seriously dif...
Mon Sep 06, 2010 3:34 pm UTC
Forum: Fit Club
Topic: Sore joints: rest up or just work them easier?
Replies: 13
Views: 3805

### Re: Sore joints: rest up or just work them easier?

Are you sure you are taking 1000mg per day, not IU? Vitamin D is fat soluble, and so the body isn't able to get rid of as much excess as water soluble vitamins, like vitamin C, which you can wolf down as much as you want of with no ill effects asides yellow pee and an empty wallet. Looking up dosage...
Fri Sep 04, 2009 2:03 pm UTC
Forum: Mathematics
Topic: Drug use and Mathematics?
Replies: 7
Views: 6784

### Re: Drug use and Mathematics?

Heard of Modafinil? I've experimented with that a bit and found it does appear to aid my ability to solve problems - though that is probably through a boost in concentration and decrease in drowsiness more than anything. http://en.wikipedia.org/wiki/Modafinil Anyone else had a similar experience? Cu...
Fri Aug 28, 2009 7:18 pm UTC
Forum: Mathematics
Topic: I may have actually made a useful function...
Replies: 20
Views: 2592

### Re: I may have actually made a useful function...

If you can actually find a use for it, what about http://arxiv.org/ ?

I'm curious, what uses do such large numbers and large number generating functions have other than just being, well, very large?
Mon Aug 17, 2009 7:12 pm UTC
Forum: Coding
Topic: Accuracy and Precision in Mathematica
Replies: 7
Views: 1603

### Re: Accuracy and Precision in Mathematica

True, I perhaps phrased what I was looking for poorly - I realise looking for accuracy is foolish, but my main motivation was to make it look neat in a table. I liked the Obama reference. How about this...instead, from an aesthetic point of view, is there a way to truncate the number displayed, with...
Fri Aug 14, 2009 2:09 pm UTC
Forum: Coding
Topic: Accuracy and Precision in Mathematica
Replies: 7
Views: 1603

### Accuracy and Precision in Mathematica

Ok, so I'm using mathematica for a project I'm doing, coding some very basic numerical methods for solving ODEs. Anyway, in my implementation for the Euler method I am iterating x from x=0 to a specified value in steps of 0.1. When it has executed: xn= xn + h 6 times or so, errors start creeping in,...
Tue May 12, 2009 1:10 pm UTC
Forum: Mathematics
Topic: A Couple of Probability Questions
Replies: 3
Views: 945

### Re: A Couple of Probability Questions

I could be wrong, but I think actually in the second case, lordofnarf meant given a probability p, how many times must we draw balls so that the probability of drawing each one at least once is greater than or equal to p, where p can be made our "arbitrary confidence level". If this is so,...
Tue May 12, 2009 12:37 am UTC
Forum: Mathematics
Topic: Cantor's Diagonalization Argument: Question
Replies: 28
Views: 2930

### Re: Cantor's Diagonalization Argument: Question

How about this then - what we are doing is saying that we can label the elements in "the set of all binary sequences" with s_0, s_1... etc, which would mean this set was countable. But by Cantors diagonal arguement, we are producing an element which is not equal to any of the s_n in this s...
Mon May 11, 2009 11:49 pm UTC
Forum: Mathematics
Topic: Help! I'm trying to get a 14 year old interested in Maths.
Replies: 52
Views: 6876

### Re: Help! I'm trying to get a 14 year old interested in Maths.

Depends on the kid, but I know when I was that age I spent most of my maths lessons asking stupid questions about infinity, so showing him the rudiments of formally arguing about infinity could be good - like the idea of mapping things into N, and countability etc.
Mon May 11, 2009 11:28 pm UTC
Forum: Mathematics
Topic: Cantor's Diagonalization Argument: Question
Replies: 28
Views: 2930

### Re: Cantor's Diagonalization Argument: Question

Hmm...I think I can see where your issues lie, your post having made me think somewhat more clearly about it in a less "formal" manner than I previously had, perhaps this post will help dig you out of your hole. Essentially, where your arguement that "but that only applies to lists of...
Thu Mar 26, 2009 4:59 pm UTC
Forum: Mathematics
Topic: Central Limit Theorem Proof
Replies: 1
Views: 681

### Central Limit Theorem Proof

http://en.wikipedia.org/wiki/Central_limit_theorem#Classical_central_limit_theorem I am having trouble 'seeing' the last step in the classical proof - where [1+(t^2)/2n + o((t^2)/n)]^n tends to e^((t^2)/2). I would be happy with the result without the little o notation, but I'm a little unclear how ...
Fri May 30, 2008 5:27 pm UTC
Forum: Mathematics
Topic: Breast Speed/Bounce equation (Not a joke)
Replies: 27
Views: 7670

### Re: Breast Speed/Bounce equation (Not a joke)

http://www.shockabsorber.co.uk/bounceometer/shock.html (NSFW link) A link I found whilst searching, I swear I heard about a group of scientists who took data and modelled the exact thing you are asking, possibly an Ignobel prize candidate? I will keep searching, but the link above may be of interest...
Mon Mar 17, 2008 6:39 pm UTC
Forum: Mathematics
Topic: Integration tips and tricks
Replies: 25
Views: 12145

### Re: Integration tips and tricks

We just use IBP and IBS if we want to shorten the names, u-substitution smacks of the sort of thing they teach the bottom sets to remember it by... no offense meant to people who know it as that, I would just say your textbooks are seem patronizing.
Wed Mar 12, 2008 7:30 pm UTC
Forum: Mathematics
Topic: Math Software
Replies: 143
Views: 166869

### Re: Can't find good math software

How about Mathematica vs Matlab - I can see both of them do a huge amount of stuff, but are there any areas one covers which the other doesn't do so well, and are there any advantages of one over the other etc?
Mon Mar 10, 2008 7:58 pm UTC
Forum: Mathematics
Topic: Math Software
Replies: 143
Views: 166869

### Re: Can't find good math software

Out of interest, out of the expensive packages, which is best?
Tue Mar 04, 2008 9:46 pm UTC
Forum: Mathematics
Topic: Integration tips and tricks
Replies: 25
Views: 12145

### Re: Integration tips and tricks

I recall that now, I think thats in 'Surely You're Joking Mr Feynman'...I meant to look it up but completely forgot! Thanks a lot...probably not that useful in single variable calculus (which is all I am doing at my level presently), but that is interesting.
Tue Mar 04, 2008 7:31 pm UTC
Forum: Mathematics
Topic: Integration tips and tricks
Replies: 25
Views: 12145

### Re: Integration tips and tricks

Ok cool, that was the way I had considered, I wondered if there was any easy way to get it even simpler...I guess thats what I'm getting at in this thread, are there any things to keep an eye out for so I don't go bashing through a really complicated integration when there is a simpler way...
Tue Mar 04, 2008 6:56 pm UTC
Forum: Mathematics
Topic: Integration tips and tricks
Replies: 25
Views: 12145

### Re: Integration tips and tricks

OK, thanks mathmagic, those are helpful ideas.

As a sideline, what sort of tricks and techniques would people here try in solving something like:

int(1/((1-cos A)2)) dA= ?
Tue Mar 04, 2008 6:11 pm UTC
Forum: Mathematics
Topic: Integration tips and tricks
Replies: 25
Views: 12145

### Integration tips and tricks

OK, well, I have to do STEP papers in July, and in practices I have frequently come across integrals which have been real bitches to do.... so, I guess my question is, does anyone have any good tips and tricks on tackling hard integrals? This may be a bit vague, but I guess it gets my question across.
Tue Mar 04, 2008 5:39 pm UTC
Forum: Mathematics
Topic: Solving Differential Equations
Replies: 13
Views: 1671

### Re: Solving Differential Equations

The last bracket on in your first line should be (a^2*b^2) instead of +...that might be the issue, and thanks for the two methods, I haven't done enough questions hard enough to consider a substitution then IBP etc.
Mon Mar 03, 2008 9:36 pm UTC
Forum: Mathematics
Topic: Solving Differential Equations
Replies: 13
Views: 1671

### Re: Solving Differential Equations

Ok, thanks for that mathmagic, I had got down to the bit just before the integration, except I struggled to integrate it without using integration by parts like a million times, perhaps we haven't covered some technique you used, but how did you integrate that function? This may be just me being ver...
Mon Mar 03, 2008 7:27 pm UTC
Forum: Mathematics
Topic: Solving Differential Equations
Replies: 13
Views: 1671

### Re: Solving Differential Equations

Literally just done this today, its a good method, I have come across similar problems before today whereby a bit of slightly intuitive massaging gets the LHS into the form required to use the product rule to integrate, but seeing how general the idea can be made only really came today. I have an in...
Thu Feb 28, 2008 10:34 pm UTC
Forum: Mathematics
Topic: Conjecture on the roots of unity
Replies: 20
Views: 2641

### Re: Conjecture on the roots of unity

Thanks, that makes more sense, so we fill in the removable discontinuity which is outside the domain of the function by using limits to define the function at that point and extend its domain, thereby getting a value for z=1.
Thu Feb 28, 2008 8:57 pm UTC
Forum: Mathematics
Topic: Conjecture on the roots of unity
Replies: 20
Views: 2641

### Re: Conjecture on the roots of unity

OK, thanks, those last few posts have really helped clear up a few things in my head. It's annoying how lacking in rigor A-level 'Calculus' really is, I can take most things an extra level than needed for the syllabus, but as soon as things start getting complex (in the C sense) it starts to fall ap...
Thu Feb 28, 2008 6:54 pm UTC
Forum: Mathematics
Topic: Conjecture on the roots of unity
Replies: 20
Views: 2641

### Re: Conjecture on the roots of unity

Ok, I understand what you've said, but how do we know p(z) is continuous, I guess how is continuity defined technically would be a more apt question... I suppose I am confusing the issue because of the fact that this is a complex function and not a real function, if this is the case then I think I f...
Thu Feb 28, 2008 5:28 pm UTC
Forum: Mathematics
Topic: Conjecture on the roots of unity
Replies: 20
Views: 2641

### Re: Conjecture on the roots of unity

Excellent, I got it in the form above which you applied l'Hopitals rule to, wasn't really sure how to take the limit but I noticed it was the formula for a geometric series 1+z 2 +...etc so thought that would be a way to show it, being n terms each of 1 when z=1, but still I lacked a way to show it ...
Tue Feb 26, 2008 7:36 pm UTC
Forum: Mathematics
Topic: Conjecture on the roots of unity
Replies: 20
Views: 2641

### Re: Conjecture on the roots of unity

I meant n to be a primitive nth root, sorry skeptical scientist, I lack a certain rigor at the moment...in that limbo between High School and University level maths, need to keep upping my standards of rigor. And thanks for the help guys, I'll try to finish it off after some STEP, damn I wish I coul...
Tue Feb 26, 2008 7:25 pm UTC
Forum: Mathematics
Topic: Conjecture on the roots of unity
Replies: 20
Views: 2641

### Re: Conjecture on the roots of unity

Ok, thanks, I will have more of a play with that form of it... I had a look at that but nothing obvious came through, so I thought a geometric argument could be worth considering. It is a really interesting problem actually, even if my geometric ideas were not the best way of going about it, it has ...
Tue Feb 26, 2008 6:30 pm UTC
Forum: Mathematics
Topic: Conjecture on the roots of unity
Replies: 20
Views: 2641

### Conjecture on the roots of unity

Ok, well in further maths the other day there were a couple of trivial exercises involving roots of unity, which the expected method of solution seemed to be just multiplying out the brackets. They were to simplify these expressions; first where w is a cube root of unity, (1-w)(1-w 2 ), which equale...
Thu Aug 09, 2007 6:18 pm UTC
Forum: Music
Topic: Listening to music backwards
Replies: 30
Views: 5970
I haven't really listened to much backwards, but Belial reminded me of MSI - I once spent a week listening to Mindless Self Indulgence at twice speed constantly. I felt strange, I can tell you that - a unique sensation.
Sun Aug 05, 2007 8:36 pm UTC
Forum: Site/Forum issues
Topic: LaTeX
Replies: 4
Views: 2243
Thats a good point actually, and I shoulda guessed that due to the fact I've been doing the same with a forum I run...still, its an idea worth raising I believe.
Sun Aug 05, 2007 8:19 pm UTC
Forum: Site/Forum issues
Topic: LaTeX
Replies: 4
Views: 2243

### LaTeX

Prehaps it would be possible to get a LaTeX mod so we can type in latex code and get it translated, I know it can be done on vBulletin forums, and there seems to be suggestion of it being possible on phpBB here: http://www.phpbb.com/community/viewtopic.php?f=17&t=94454&st=0&sk=t&sd=a...
Sun Aug 05, 2007 6:35 pm UTC
Forum: Mathematics
Topic: Maths and MSN
Replies: 19
Views: 4575
Thanks for the input, there are some awesomely useful tools in there, but especially thanks to Ikari-Kun for sharing aMSN - the plugin is awesome, exactly what I wanted (and indeed what I would reccomend for anyone wanting maths and MSN as opposed to another IM, for me it would simply be too awkward...
Sat Jul 28, 2007 1:10 am UTC
Forum: Mathematics
Topic: Simple Algebra Question.. Help Please
Replies: 7
Views: 1821
Are we dealing in integers, ie can the metronome only accept integer values for each of the unknowns in "x beats every y seconds"?
Fri Jul 27, 2007 11:15 pm UTC
Forum: Science
Topic: Lets fix global warming.
Replies: 239
Views: 22905
Solar powered, self sustainable planes with algae attached. Would need a system for removing overflowing algae and burying.
Thu Jul 26, 2007 8:20 am UTC
Forum: Mathematics
Topic: Mechanics of pressups
Replies: 19
Views: 2609
Cool stuff, thanks.