Recent content by ascky

How unintuitive! Thanks for that Bill, I wouldn't have figured it out on my own.

So I want to be able to count the number of neighbour pairs of opposite sign in a list of 1's and -1's (eg. 1 for {1,1,1,-1,-1} and 3 for {1,-1,1,-1,-1}), but I can't work out the pattern matching syntax in Mathematica even after reading the documentation. I was thinking to use the Count...

Ahhh I get it now. That was very clear. :smile: Thanks very much for your help. Now I can sleep contentedly!

I'm having trouble with the algebra manipulating that substitution to get it nicely as \int \frac{4u^2}{(1+u^2)^2} du Would it be too much trouble to explain how you did that? Of course from there, it's nice.

Oh, gee, I copied it wrong. How embarrassing. My apologies. How about \int \frac{\sqrt{\frac{x-1}{x+1}}}{x^2} dx Wolfram thinks it's arctan-ny.

I've been trying to figure this out for a while, but I can't find the right substitution: \int \sqrt{\frac{x-1}{x(x+1)}} dx Anyone able to help me out? It's driving me crazy.

I read somewhere that when the cats reach terminal velocity, because they're not accelerating anymore, they relax and therefore aren't so tense when they land, reducing injury. Don't know if that's true.

I started reading Lectures on Electrical Engineering Vol I, Steinmetz. I thought I should be able to understand most of it, but I don't get the first page! It says that: 'The total number of lines of force issuing from a magnet pole is called its magnetic flux. The magnetic flux, phi, of a...

'Since basically everyone on this forum doubts me and thinks I said I'm some super intelligent genius (Which I never, ever said) I'm sure people will doubt I can type this fast.' Why do you assume others make an immediate link between ingelligence and fast typing? That's an insult to their...

Sorry, I'm not really answering the question; just thought I'd say hi to a fellow victorian. I'm planning on going to melb uni next year. Partly I won't get into that 99.3 monash course either, and partly because I'm doing enhancement physics (run by melb uni), so it's the natural progression. I...

I can only think of a dubious way that doesn't use gravity. If you cut two rubber bands into strips and stretch them over the top and bottom of a timer balloon <O>, then when the ballooon runs out of air, the bands won't be pulling so strongly. So if you have two side balloons o<O>o, and...

So how would one go about calculating the wavelength of, say, a dc electric field?

I'm confused as to how the concept that 'things' have a wavelength applies to an electromagnetic field, which has momentum, but not mass: what 'things' have wavelengths? Are there other criteria, other than whether something has mass or momentum, that must be fufilled before talking about...

nvm.. I got it (yay) :smile:

Is there a way to get the Taylor series of 1/sqrt(cosx), without using the direct f(x)=f(0)+xf'(0)+(x^2/2!)f''(0)+(x^3/3!)f'''(0)... form, just by manipulating it if you already know the series for cosx?