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#math
<Jafet> It's less general than XOR, and slower to boot.
<thianpa> and a = a-b and b= a-b
<Jafet> It's only value is as a curosity.
<thianpa> but its simple if the value is passed in itself
<brick_> Ok I still can't seem to get this - I've got the power series of Sin(.45) ... (-1)^n * (.45)^(2n+1)/(2n+1)! and I need to find out at what term the term is .0000001
<brick_> it seems like I just need to solve .0000001 == (.45)*(.45)^(2n) / (2n+1)!
<brick_> but i dont know how to work with factorials in algebra
<me22> guess and check
<seb-_> brick_: write a computer script and brute force it?
<seb-_> % 2 + 4
<brick_> haha these are both good methods it just seems like it'd take a while -- i was wondering if there was some easy formula
<seb-_> brick_: our method is easy
<seb-_> brick_: and fast
<seb-_> brick_: no there is no tricks to massage factorials into anything else that i know of
<phrontist> does anyone know where I can find info about how computer algebra systems work?
<woggle> seb-_: Stirling's approximation gets pretty close for many purposes.
<seb-_> phrontist: google?....there is also a nice 2 volume set called "C. A."
<seb-_> woogle: for big n
<seb-_> woogle: iirc
<Steve|Office> Stirling's approximation is wildly inaccurate. But the numbers it deals with are so large that the error is quite small.
<me22> brick_: it's probably around 5 or 6 terms. just binary search it and it wont take many guesses
<brick_> yeah it's 4
<brick_> haha
<brick_> I guess I was just looking for a way to find it algebraically but as you said that'd involve massaging factorials somehow
<jerware> where can i find a picture of a Q5 graph ?
<Jafet> _brick: it doesn't work that way. The remainder of the terms, though each smaller than x, could add up to be far more than x.
<asphyxia> gzl: still there?
<cerealkiller219> anyone care to walk me through the steps for solving the dirivative of 4(x+1) / 3x^(2/3)
<me22> Jafet: but it's an alternating series and the magnitudes of the terms are monotonically decreasing
<gzl> kind of
<me22> cerealkiller219: find derivatives of the numerator and denominator, then use quotient rule
<cerealkiller219> ive been trying
<asphyxia> cerealkiller219: the syntax is (f/g) = (f'g + g'f)/(g)^2.
<cerealkiller219> I am aware of that
<cerealkiller219> But I cannot get the answer
<cerealkiller219> I'm doing something wrong but I'm not sure where
<asphyxia> find f'
<asphyxia> find g'
<asphyxia> then you have your answer.
<asphyxia> oh, btw, in the numerator, it is - not plus
<asphyxia> the only way you can run into trouble is if you dont know how to derive f or g
<cerealkiller219> would the deriv of 4(x+1) be 4(x+1)^-1 * 1 or just (1) * (1)
<cerealkiller219> its been too long since if done them I don't rememer the rules of derivatives
<mahamoti> anybody heard of the runs or chi-squared tests?
<cerealkiller219> besides quotient and product rule
<asphyxia> mahamoti: thats statistics
<mahamoti> d/dx 4(x+1) = 4
<mahamoti> asphyxia: yes, it is...is there a separate statistics forum?
<asphyxia> I guess. efnet has a very inactive one
<cerealkiller219> thanks mahamtoi
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