#8553: Minor bugs in solve() if dictionary result requested
-------------------------------------------------------------------------------+
Reporter: leif
| Owner: leif
Type: defect
| Status: positive_review
Priority: trivial
| Milestone: sage-4.7.1
Component: symbolics
| Keywords: solve, solution_dict, beginner
Work_issues:
| Upstream: N/A
Reviewer: Harald Schilly, Mike Hansen, Burcin Erocal, Karl-Dieter Crisman
| Author: Leif Leonhardy
Merged:
| Dependencies:
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Changes (by kcrisman):
* status: needs_work => positive_review
* reviewer: Harald Schilly, Mike Hansen, Burcin Erocal => Harald
Schilly, Mike Hansen, Burcin Erocal, Karl-
Dieter Crisman
* milestone: sage-4.7 => sage-4.7.1
Old description:
> {{{solve()}}} raises an {{{IndexError}}} on empty solutions if a list of
> solution ''dictionaries'' is requested.
>
> The description/examples may mislead w.r.t. the result type.
New description:
{{{solve()}}} raises an {{{IndexError}}} on empty solutions if a list of
solution ''dictionaries'' is requested.
The description/examples may mislead w.r.t. the result type.
----
Apply [attachment:trac_8553_solve_fix_IndexError.3.patch] and
[attachment:trac_8553-review.patch].
--
Comment:
Replying to [comment:30 leif]:
> Replying to [comment:28 burcin]:
> > Can you review my changes BTW?
>
> {{{m.to_poly_solve(variables)}}} might be called twice.
It is, but only in the unusual situation that Maxima's solve gave an error
and `to_poly_solve` gave the empty list. More to the point, this was
there before, and should be a different ticket.
> Btw, I think the patch should be finally reviewed by someone else, not
me, as I'm one of the authors.
>
Not at all - usually it is appropriate to review a reviewer patch. This
reviewer patch really is pretty minimally invasive, and in fact provides a
much more useful error message.
It is true that
{{{
sage: solve(x==1,x,solution_dict=int(3))
[{x: 1}]
sage: solve([0==1],x,solution_dict=int(3))
[]
sage: solve(0==1,x,solution_dict=int(3))
---------------------------------------------------------------------------
TypeError Traceback (most recent call
last)
/Users/karl-dietercrisman/Downloads/sage-4.7.rc1/<ipython console> in
<module>()
/Users/karl-dietercrisman/Downloads/sage-4.7.rc1/local/lib/python2.6/site-
packages/sage/symbolic/relation.pyc in solve(f, *args, **kwds)
652
653 if not isinstance(f, (list, tuple)):
--> 654 raise TypeError("The first argument must be a symbolic
expression or a list of symbolic expressions.")
655
656 if len(f)==1 and is_Expression(f[0]):
TypeError: The first argument must be a symbolic expression or a list of
symbolic expressions.
}}}
which is not ideal. However, this is still better behavior than the
mysterious message about bools and len before, so that could be another
ticket.
In any case, this (somewhat surprisingly) still applies fine to 4.7.rc2!
And does what it says. And passes tests. Positive review.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/8553#comment:33>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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