MaximaElements should not coerce into SR.

[mwhansen]

sage: f = maxima.function('x','sin(x)')
sage: f + x  #correct
sin(x)+x
sage: x+f    #wrong
x + sage6

Component: calculus

Author: Mike Hansen

Reviewer: Adam Webb

Merged: sage-4.2.alpha0

Issue created by migration from https://trac.sagemath.org/ticket/3970

[mwhansen]

comment:1

After:

sage: f = maxima.function('x','sin(x)')
sage: f+x
sin(x)+x
sage: x+f
sin(x)+x
sage: type(_)
<class 'sage.interfaces.maxima.MaximaFunction'>

[mwhansen]

comment:2

Patch added which fixes the issue. This depends on #132.

[mwhansen]

comment:3

This patch actually breaks everything in calculus.py. I must have ran the tests without having it actually applied.

[jasongrout]

comment:4

What is the status of this now? Apparently it still is a problem in 4.0:

----------------------------------------------------------------------
| Sage Version 4.0, Release Date: 2009-05-29                         |
| Type notebook() for the GUI, and license() for information.        |
----------------------------------------------------------------------
sage: f = maxima.function('x','sin(x)')
sage: f + x  #correct
sin(x)+x
sage: x+f    #wrong
sage0 + x
sage: 

[mwhansen]

Author: Mike Hansen

[maxthemouse]

comment:6

I get an error with sage -t -long sage/symbolic/ring.pyx. I am not sure that I understand the patch as it seems to apply for both maxima and pari. Is this by intention?

sage -t -long "devel/sage-myver/sage/symbolic/ring.pyx"
**********************************************************************
File "/home/adamwebb/local/sage/devel/sage-myver/sage/symbolic/ring.pyx", line 97:
    sage: SR.coerce(pari(2/5))
Exception raised:
    Traceback (most recent call last):
      File "/home/adamwebb/local/sage/local/bin/ncadoctest.py", line 1231, in run_one_test
        self.run_one_example(test, example, filename, compileflags)
      File "/home/adamwebb/local/sage/local/bin/sagedoctest.py", line 38, in run_one_example
        OrigDocTestRunner.run_one_example(self, test, example, filename, compileflags)
      File "/home/adamwebb/local/sage/local/bin/ncadoctest.py", line 1172, in run_one_example
        compileflags, 1) in test.globs
      File "<doctest __main__.example_7[3]>", line 1, in <module>
        SR.coerce(pari(Integer(2)/Integer(5)))###line 97:
    sage: SR.coerce(pari(2/5))
      File "parent.pyx", line 402, in sage.structure.parent.Parent.coerce (sage/structure/parent.c:4859)
      File "parent.pyx", line 429, in sage.structure.parent.Parent.coerce (sage/structure/parent.c:4806)
    TypeError: no canonical coercion from Interface to the PARI C library to Symbolic Ring
**********************************************************************
1 items had failures:
   1 of  12 in __main__.example_7
***Test Failed*** 1 failures.

if I put back the Pari stuff:

from sage.libs.pari.gen import PariInstance

elif isinstance(R, (PariInstance)): 
    return True

Then everything works.

Cheers,
Adam

[mwhansen]

comment:7

Attachment: trac_3970.patch.gz

I forgot to remove the pari doctest. It should also be removed since these parents should not have coercions going in both directions.

This is taken care of in the new patch.

[maxthemouse]

comment:8

In that case, everything looks good. A quick retest also passes. ~ Adam

[maxthemouse]

Reviewer: Adam Webb

[mwhansen]

Merged: sage-4.2.alpha0