#12796: Allow more general evaluation of FDerivativeOperator
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Reporter: nbruin | Owner: burcin
Type: enhancement | Status: new
Priority: major | Milestone: sage-5.0
Component: symbolics | Resolution:
Keywords: | Work issues:
Report Upstream: N/A | Reviewers:
Authors: | Merged in:
Dependencies: | Stopgaps:
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Comment (by nbruin):
With the attached patch we have:
{{{
sage: f=function('f')
sage: g=function('g')
sage: fx=diff(f(x),x).operator()
sage: fx(g(x))
D[0](f)(g(x))
sage: I=fx(g(x)).integrate(x)
sage: I
integrate(D[0](f)(g(x)), x)
}}}
but unfortunately:
{{{
sage: I.simplify()
TypeError: unable to make sense of Maxima expression
'integrate(at(diff(f(t0),t0,1),[t0=g(x)]),x)' in Sage
}}}
The problem here is in `symbolic_expression_from_maxima_string`. Maxima's
syntax allows a sequence as an argument for multiple substitutions, but
the string-based parser is unable to handle that.
`max_to_sr` and `sr_to_max` do the trick already, which is why "I" can be
defined in the first place. `simplify` still uses the strings-based
conversion, hence the problem. Any experts on the parser of maxima strings
want to weigh in? In short, the maxima expression
{{{
at( f(x,y,z), [x=u,y=v,z=w])
}}}
is valid, but is currently not accepted by the string-based parser.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/12796#comment:1>
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