#10940: giac interface
----------------------------+-----------------------------------------------
Reporter: Han Frederic | Owner: kohel
Type: enhancement | Status: needs_work
Priority: minor | Milestone: sage-4.7.2
Component: interfaces | Keywords: giac, interfaces
Work_issues: | Upstream: N/A
Reviewer: David Kohel | Author: Frederic Han
Merged: | Dependencies:
----------------------------+-----------------------------------------------
Changes (by newvalueoldvalue):
* status: needs_review => needs_work
* reviewer: => David Kohel
* author: => Frederic Han
Comment:
This adds a new interface (based on maple.py) to the
giac library:
http://www-fourier.ujf-grenoble.fr/~parisse/giac.html
This library, in the form of the graphical interface
xcas, is widely used in the France competitive exams
for high school teachers, hence widely tested.
The new interface is fully documented, more examples
of usage are found here:
http://www.math.jussieu.fr/~han/exemples-giac%20--%20Sage.html
I identified one error in preparing the patch: 'giac'
needs to be added to interfaces at the end of all.py.
A simple pre-parsing would improve the interface:
sage: s = """
my_mod(a,b) := {
return irem(a,b)
}
"""
sage: giac(s)
<error>
However, reducing to one line works:
sage: giac(s.replace("\n",""))
(a,b)->{
return(irem(a,b));
}
sage: giac("my_mod(103,101)")
2
or similarly one can insert \'s:
sage: giac(s.replace("\n","\\"))
(a,b)->{
return(irem(a,b));
}
sage: giac("my_mod(103,101)")
2
Caution: I don't know if the giac
parser always ignores "\n", and in
the second replacement some more
care is needed to avoid replacing
"\\\n" with "\\\\".
The example given on the above site is:
%giac
f:=(a,b)-> if (a<b) \
then x[a,b]; \
else if (a>b) \
then -x[b,a]; \
else 0; \
fi;\
fi;
Given that giac uses ";" to terminate lines,
a better pre-parsing would render the \'s
unnecessary, as is the case for the xcas
interpretter.
It should be noted that conversions back to
Sage are limited. As far as I can tell only
automatic string evaluations succeed (but
errors are trapped and this is documented).
Finally, the author notes that an interrupt
in Sage can kill the giac session.
Extending conversions to Sage and handling
interrupts better are larger projects which
could be done later. Rebuilding the diff
to recover the %giac magic feature and some
slight pre-parsing would be desirable to
complete this interface.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/10940#comment:5>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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