Re: [sage-support] Residue of the exponential function

2015-11-06 Thread Rob Beezer
Dear Nils, Thanks for the careful explanation. There's a good reason I don't teach this stuff (even if I enjoy it!). Rob On Thursday, November 5, 2015 at 7:35:47 PM UTC-8, Nils Bruin wrote: > > On Thursday, November 5, 2015 at 5:11:42 PM UTC-8, Rob Beezer wrote: >> >> LIke I said, my complex a

Re: [sage-support] Residue of the exponential function

2015-11-05 Thread Nils Bruin
On Thursday, November 5, 2015 at 5:11:42 PM UTC-8, Rob Beezer wrote: > > LIke I said, my complex analysis is rusty. And I am really asking for > somebody else. Is the chunk of code that produces 2 (above) not following > the definition of the residue? > No it's not. If t=1/z then you don't get

Re: [sage-support] Residue of the exponential function

2015-11-05 Thread Rob Beezer
Thanks, John. Allowable syntax is residue(z) or residue(z == 0). The former defaults to using 0, so they should be equivalent and both forms give the same result. LIke I said, my complex analysis is rusty. And I am really asking for somebody else. Is the chunk of code that produces 2 (ab

Re: [sage-support] Residue of the exponential function

2015-11-05 Thread John Cremona
Why are you giving the argument z to the residue function ? If you wanted the residue at 0 put that. But exp (2/z) is not meromorphic at 0 so the residue there is surely undefined ? On Nov 5, 2015 3:53 AM, "Rob Beezer" wrote: > > > On Wednesday, November 4, 2015 at 7:37:58 PM UTC-8, vdelecroix

Re: [sage-support] Residue of the exponential function

2015-11-04 Thread Rob Beezer
On Wednesday, November 4, 2015 at 7:37:58 PM UTC-8, vdelecroix wrote: > > z/2 vs 2/z > Ouch! Sorry. Wrong input, same output. z = var('z') f = e^(2/z) f.residue(z) Result: 0 -- You received this message because you are subscribed to the Google Groups "sage-support" group. To unsubscribe

Re: [sage-support] Residue of the exponential function

2015-11-04 Thread Vincent Delecroix
z/2 vs 2/z On 05/11/15 00:32, Rob Beezer wrote: My complex analysis is very rusty, so I can't tell if the problem here is me or Sage: z = var('z') f = e^(z/2) f.residue(z) Result: 0 x = var('x') g = e^x t = g.taylor(x, 0, 5) t(x = 2/z) Result: 2/z + 2/z^2 + 4/3/z^3 + 2/3/z^4 + 4/15/z^5 + 1

[sage-support] Residue of the exponential function

2015-11-04 Thread Rob Beezer
My complex analysis is very rusty, so I can't tell if the problem here is me or Sage: z = var('z') f = e^(z/2) f.residue(z) Result: 0 x = var('x') g = e^x t = g.taylor(x, 0, 5) t(x = 2/z) Result: 2/z + 2/z^2 + 4/3/z^3 + 2/3/z^4 + 4/15/z^5 + 1 So the coefficient of 1/z is 2, and the residue sh