#12801: substitute_function misses some substitutions
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Reporter: nbruin | Owner: burcin
Type: defect | Status: positive_review
Priority: minor | Milestone: sage-5.0
Component: symbolics | Resolution:
Keywords: | Work issues:
Report Upstream: N/A | Reviewers: Michael Orlitzky
Authors: | Merged in:
Dependencies: #12796 | Stopgaps:
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Changes (by nbruin):
* status: needs_review => positive_review
Old description:
> Works correctly:
> {{{
> sage: f=function('f')
> sage: g=function('g')
> sage: (f(g(x))+g(x)).substitute_function(g,sin)
> sin(x) + f(sin(x))
> }}}
> but
> {{{
> sage: f(g(x)).diff(x).substitute_function(g,sin)
> cos(x)*D[0](f)(g(x))
> sage:
> sage.symbolic.operators.FDerivativeOperator(f,[0])(g(x)).substitute_function(g,sin)
> D[0](f)(g(x))
> }}}
> so I suspect it forgets to descend into the arguments of an
> FDerivativeOperator
New description:
Works correctly:
{{{
sage: f=function('f')
sage: g=function('g')
sage: (f(g(x))+g(x)).substitute_function(g,sin)
sin(x) + f(sin(x))
}}}
but
{{{
sage: f(g(x)).diff(x).substitute_function(g,sin)
cos(x)*D[0](f)(g(x))
sage:
sage.symbolic.operators.FDerivativeOperator(f,[0])(g(x)).substitute_function(g,sin)
D[0](f)(g(x))
}}}
so I suspect it forgets to descend into the arguments of an
FDerivativeOperator
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Apply [attachment:12801.patch], [attachment:sage-trac_12801-review.patch].
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Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/12801#comment:8>
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