ASKSAGE: Sage Q&A Forum - RSS feedhttps://ask.sagemath.org/questions/Q&A Forum for SageenCopyright Sage, 2010. Some rights reserved under creative commons license.Wed, 03 Jul 2013 11:30:22 +0200desolve_system problem with exp()/e^https://ask.sagemath.org/question/10315/desolve_system-problem-with-expe/Hi!
I'm trying to solve ode system:
x'=-2x+2y+e^t,
y'=-2x+3y+3e^t
This is what I tried in Sage:
>reset()
>var('t')
>x = function('x', t)
>y = function('y', t)
>dgl1 = x.diff(t) == -2 * x + 2 * y + exp(t)
>dgl2 = y.diff(t) == -2 * x + 3 * y + 3 * exp(t)
>dgls = [dgl1, dgl2]
>aw = [0, 0, -1]
>S = desolve_system(dgls, [x, y], aw)
But I always get this error:
>Traceback (click to the left of this block for traceback)
>...
>TypeError: ECL says: Maxima asks: Is ?g9271-1 positive, negative, or
zero?
If I remove the exp(t) it works fine, also if I replace the exp(t) with for example 2^t Sage gives me a solution. I already tried using e^t instead of exp(t) and tried some assumptions (assume(x >= 0), assume(t >= 0), etc.). Anyone got an idea what I'm doing wrong? Thanks in advance!TeHeRu33Wed, 03 Jul 2013 11:30:22 +0200https://ask.sagemath.org/question/10315/