#6376: serious bug in _maxima_init_ method for formal derivatives with new
symbolics
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Reporter: was | Owner: burcin
Type: defect | Status: new
Priority: critical | Milestone: sage-4.1
Component: calculus | Keywords:
Reviewer: | Author:
Merged: |
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{{{
sage: f(x) = function('f',x)
sage: g = f(-x).diff(x); g
-D[0](f)(-x)
sage: g._maxima_init_()
"(diff('f(x), x, 1))*(-1)"
}}}
Notice that the {{{-x}}} inside f is totally ignored! This is because of
code in the derivative method around line 454 of
{{{sage/symbolic/expression_conversion.py}}}
Changing the line
{{{
args = ex.args()
}}}
to
{{{
args = ex.operands()
}}}
"fixes" the problem, in that a NotImplementedError gets raised, instead of
a wrong result returned. This is '''way''' better than the current
situation, and we better fix this asap.
A better fix of course is to implement proper conversion. mhansen wrote
this code, so maybe it would be easy for him.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/6376>
Sage <http://sagemath.org/>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
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