#16732: Fix translation of psi(x,y) to/from maxima
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Reporter: nbruin | Owner:
Type: defect | Status: new
Priority: minor | Milestone: sage-6.3
Component: interfaces | Keywords:
Merged in: | Authors:
Reviewers: | Report Upstream: N/A
Work issues: | Branch:
Commit: | Dependencies:
Stopgaps: |
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Follow-up to #9217. We have some imperfect translations to/from maxima of
`psi(x,y)`. The template is:
{{{
sage: x,y=var("x y")
sage: maxima_calculus(psi(x,y))
psi[x](y)
}}}
The conversion doesn't seem to completely recurse on the first argument,
though:
{{{
sage: maxima_calculus(psi(psi(x,y),y))
psi[psi(x,y)](y)
}}}
(note that the inner psi does not have the square brackets)
Round-tripping only works for completely numeric first arguments (as per
how the responsible regexp is designed):
{{{
sage: maxima_calculus(psi(x,y))._sage_()
TypeError: unable to make sense of Maxima expression 'psi[x](y)' in Sage
}}}
These conversions all go fine with the tree-walking translation of
maxima_lib (which gets used for some, but not all calculus operations):
{{{
sage: from sage.interfaces.maxima_lib import sr_to_max,max_to_sr
sage: T=maxima_calculus(sr_to_max(psi(psi(x,y),y))); T
psi[psi[x](y)](y)
sage: max_to_sr(T.ecl())
psi(psi(x, y), y)
}}}
Note that the regex-based "._sage_()" conversion will fundamentally have
trouble with nested square brackets:
{{{
sage: T._sage_()
TypeError: unable to make sense of Maxima expression 'psi[psi[x](y)](y)'
in Sage
}}}
As a first step we might want to change the regex to accept "non-]" inside
the square brackets to allow translation with non-numeric parameters. I
don't think anybody has seen an expression in the wild yet that has nested
square brackets (indeed, mostly the parameter is explicit numeric).
There are some other maxima functions that use square brackets too. These
might benefit from a similar treatment.
--
Ticket URL: <http://trac.sagemath.org/ticket/16732>
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