#8969: problems with maxima inequalities
----------------------------------+-----------------------------------------
Reporter: dsm | Owner: burcin
Type: defect | Status: needs_review
Priority: minor | Milestone:
Component: symbolics | Resolution:
Keywords: sd40.5 | Work issues:
Report Upstream: N/A | Reviewers:
Authors: Douglas McNeil | Merged in:
Dependencies: | Stopgaps:
----------------------------------+-----------------------------------------
Changes (by {'newvalue': u'Douglas McNeil', 'oldvalue': ''}):
* keywords: => sd40.5
* status: new => needs_review
* author: => Douglas McNeil
Old description:
> 'Sage Version 4.4.1, Release Date: 2010-05-02'
>
> mac 10.4 32 bit running on 10.5.8.
> {{{
> sage: solve([2*x==3, x < 10], x)
> [[x == (3/2)]]
> sage: solve([2*x==3, x > 10], x)
> []
> sage: solve([2*x==3, x == 10], x)
> []
> sage: solve([2*x==3, x == 3/2], x)
> [[x == (3/2)]]
>
> sage: solve([2*x==3, x < 4, x > 4], x)
> []
> }}}
> all work as expected, but:
> {{{
> sage: solve([2*x==3, x != 5], x)
> -----------------------------------------------------------
> !TypeError Traceback (most recent call
> last)
>
> /Applications/sage/devel/sage-main/build/sage/<ipython console> in
> <module>()
> /Applications/sage/local/lib/python2.6/site-
> packages/sage/symbolic/relation.pyc in solve(f, *args, **kwds)
> 670 s = []
> 671
> --> 672 sol_list = string_to_list_of_solutions(repr(s))
> 673 if 'solution_dict' in kwds and
> kwds!['solution_dict']==True:
> 674 if isinstance(sol_list![0], list):
> ]/Applications/sage/local/lib/python2.6/site-
> packages/sage/symbolic/relation.pyc in string_to_list_of_solutions(s)
> 455 from sage.structure.sequence import Sequence
> 456 from sage.calculus.calculus import
> symbolic_expression_from_maxima_string
> --> 457 v = symbolic_expression_from_maxima_string(s,
> equals_sub=True)
> 458 return Sequence(v, universe=Objects(), cr_str=True)
> 459
> /Applications/sage/local/lib/python2.6/site-
> packages/sage/calculus/calculus.py in
> symbolic_expression_from_maxima_string(x, equals_sub, maxima)
> 1527 return symbolic_expression_from_string(s, syms,
> accept_sequence=True)
> 1528 except !!!!SyntaxError:
> -> 1529 raise !TypeError, "unable to make sense of Maxima
> expression '%s' in Sage"%s
> 1530 finally:
> 1531 is_simplified = False
> !TypeError: unable to make sense of Maxima expression
> '[[x==3/2,-7/2!==0]]' in Sage
> }}}
> --
>
> The `!==` which is causing trouble is due to the
> {{{
> if equals_sub:
> s = s.replace('=','==')
> }}}
> lines in `symbolic_expression_from_maxima_string`. This could be fixed
> by changing the replace to a regexp, or adding a hack `s =
> s.replace('!==', '!=')` afterwards.
>
> This deals with the obvious problem but not the underlying one, which is
> that the result is still IMHO underprocessed:
> {{{
> MODIFIED_sage: solve([2*x==3, x != 4], x)[[BR]][[x == (3/2), (-5/2) !=
> 0]]
>
> when I wanted [[x == (3/2)]], or
>
> MODIFIED_sage: solve([2*x==3, x != 3/2], x)[[BR]][[x == (3/2), 0 != 0]]
>
> when I wanted [].
> }}}
> In fact, even in cases not involving "!=", it's possible for maxima
> output -- %union([x = 3/2, -5/2 # 0]) -- to be insufficiently
> processed,IMHO:
> {{{
> MODIFIED_sage: solve([2*x==3, (x-4)!^2 > 0], x)
> [[x == (3/2), (-5/2) != 0]]
> }}}
> ISTM the extra information about what condition maxima used isn't worth
> the inconvenience of having to postprocess the solutions to see if one
> exists.
New description:
'Sage Version 4.4.1, Release Date: 2010-05-02'
mac 10.4 32 bit running on 10.5.8.
{{{
sage: solve([2*x==3, x < 10], x)
[[x == (3/2)]]
sage: solve([2*x==3, x > 10], x)
[]
sage: solve([2*x==3, x == 10], x)
[]
sage: solve([2*x==3, x == 3/2], x)
[[x == (3/2)]]
sage: solve([2*x==3, x < 4, x > 4], x)
[]
}}}
all work as expected, but:
{{{
sage: solve([2*x==3, x != 5], x)
-----------------------------------------------------------
!TypeError Traceback (most recent call
last)
/Applications/sage/devel/sage-main/build/sage/<ipython console> in
<module>()
/Applications/sage/local/lib/python2.6/site-
packages/sage/symbolic/relation.pyc in solve(f, *args, **kwds)
670 s = []
671
--> 672 sol_list = string_to_list_of_solutions(repr(s))
673 if 'solution_dict' in kwds and
kwds!['solution_dict']==True:
674 if isinstance(sol_list![0], list):
]/Applications/sage/local/lib/python2.6/site-
packages/sage/symbolic/relation.pyc in string_to_list_of_solutions(s)
455 from sage.structure.sequence import Sequence
456 from sage.calculus.calculus import
symbolic_expression_from_maxima_string
--> 457 v = symbolic_expression_from_maxima_string(s, equals_sub=True)
458 return Sequence(v, universe=Objects(), cr_str=True)
459
/Applications/sage/local/lib/python2.6/site-
packages/sage/calculus/calculus.py in
symbolic_expression_from_maxima_string(x, equals_sub, maxima)
1527 return symbolic_expression_from_string(s, syms,
accept_sequence=True)
1528 except !!!!SyntaxError:
-> 1529 raise !TypeError, "unable to make sense of Maxima
expression '%s' in Sage"%s
1530 finally:
1531 is_simplified = False
!TypeError: unable to make sense of Maxima expression
'[[x==3/2,-7/2!==0]]' in Sage
}}}
--
The `!==` which is causing trouble is due to the
{{{
if equals_sub:
s = s.replace('=','==')
}}}
lines in `symbolic_expression_from_maxima_string`. This could be fixed
by changing the replace to a regexp, or adding a hack `s =
s.replace('!==', '!=')` afterwards.
--
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/8969#comment:3>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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