ASKSAGE: Sage Q&A Forum - Latest question feedhttp://ask.sagemath.org/questions/Q&A Forum for SageenCopyright Sage, 2010. Some rights reserved under creative commons license.Wed, 28 Jan 2015 17:03:45 -0600Cannot desolve ODEhttp://ask.sagemath.org/question/25632/cannot-desolve-ode/ I'm trying to compute the solution for a first order differential equation using the code below:
var('g, a, v_e, m_0, v_9, k')
m(t) = (m_0 - a*t)
v = function('v', t)
de = m*diff(v, t) == -v_e*diff(m, t) - k*v - m*g
ans = desolve(de, v, ics=[0,0], ivar=t)
This returns the following error:
TypeError: Computation failed since Maxima requested additional constraints; using the 'assume' command before evaluation *may* help (example of legal syntax is 'assume(-k/a>0)', see `assume?` for more details)
Running assume(-k/a>0) before desolve does not remove the error. This error does not happen with the k*v term removed. By hand, I was able to solve this DE using integrating factors.
lscottWed, 28 Jan 2015 17:03:45 -0600http://ask.sagemath.org/question/25632/TypeError: ECL says: Maxima asks: Is y positive, negative, or zero?http://ask.sagemath.org/question/10636/typeerror-ecl-says-maxima-asks-is-y-positive-negative-or-zero/I'm using sage to give me the inverse of functions using solve(). Most of the time, it works fine. But when I have roots of anything involved(for example, "solve((5x-2)^(1/7)==y,x)", I get the error message in the title. Is there any way around this?SnapSun, 20 Oct 2013 03:22:35 -0500http://ask.sagemath.org/question/10636/Problems with LaPlace transform when 'a' is negative in e^-athttp://ask.sagemath.org/question/8908/problems-with-laplace-transform-when-a-is-negative-in-e-at/ var('s t')
f = t^(-1)*exp(-t)-t^(-1)*exp((-3)*t)
f.laplace(t,s)
The above transform works as expected, however, when (-3) is changed to (3), I get the following error:
Traceback (click to the left of this block for traceback)
...
TypeError: ECL says: Maxima asks: Is s-3 positive, negative, or zero?
The Solution that I am expecting is:
log((s - 3)/(s + 1))
I don't know how to specify if s-3 is positive, negative, or zero. Any ideas?
Thanks,
Taylor Killian
tkillianThu, 19 Apr 2012 17:39:03 -0500http://ask.sagemath.org/question/8908/TypeError: Computation failed since Maxima requested additional constraintshttp://ask.sagemath.org/question/8340/typeerror-computation-failed-since-maxima-requested-additional-constraints/I have the following code:
N, n, f = var('N, n, f')
assume(N>0)
sum(binomial(N, n)*f^n*(1-f)^(N-n), n, (N+1)/2, N)
It gives me the following error message:
TypeError: Computation failed since Maxima requested additional constraints (try the command 'assume(N+1>0)' before integral or limit evaluation, for example): Is N+1 positive, negative, or zero?ckThu, 22 Sep 2011 07:56:11 -0500http://ask.sagemath.org/question/8340/