#3914: error in parsing maxima output
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Reporter: jason | Owner: was
Type: defect | Status: new
Priority: major | Milestone: sage-4.1.2
Component: interfaces | Keywords:
Reviewer: | Author:
Merged: |
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Comment(by kcrisman):
The errors are now slightly different post-Pynac switch, but here is the
real issue.
{{{
sage: var('t,s')
(t, s)
sage: f = function('f',t)
sage: g = f.diff(t,2)
sage: h = f.diff(t,1)
sage: f.laplace(t,s)
laplace(f(t), t, s)
sage: h.laplace(t,s)
s*laplace(f(t), t, s) - f(0)
sage: SR(f)._maxima_().laplace(var('t'), var('s'))
'laplace('f(t),t,s)
sage: SR(h)._maxima_().laplace(var('t'), var('s'))
s*'laplace('f(t),t,s)-'f(0)
sage: SR(g)._maxima_().laplace(var('t'), var('s'))
-?%at('diff('f(t),t,1),t=0)+s^2*'laplace('f(t),t,s)-'f(0)*s
}}}
Sage has no chance to parse that! And here is what it means:
{{{
Maxima 5.19.1 http://maxima.sourceforge.net
Using Lisp SBCL 1.0.30
Distributed under the GNU Public License. See the file COPYING.
Dedicated to the memory of William Schelter.
The function bug_report() provides bug reporting information.
(%i1) diff(f(t),t,2);
2
d
(%o1) --- (f(t))
2
dt
(%i2) laplace(%,t,s);
!
d ! 2
(%o2) - -- (f(t))! + s laplace(f(t), t, s) - f(0) s
dt !
!t = 0
}}}
So Maxima is trying to evaluate the derivative of f at t=0, which Sage
doesn't know how to evaluate. Do we have syntax for that? I think that
{{{
sage: h.subs(t=0)
D[0](f)(0)
}}}
might not be what we are looking for. Anyway, we definitely would have
to improve our handling of the output from Maxima in order to get this
right.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/3914#comment:1>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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