#16587: f(expr).n() fails for all generalized functions
-----------------------------------+------------------------
Reporter: rws | Owner:
Type: defect | Status: new
Priority: major | Milestone: sage-6.4
Component: symbolics | Resolution:
Keywords: sgn, evaluation | Merged in:
Authors: | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
Dependencies: | Stopgaps:
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Comment (by rws):
Actually all functions in `generalized.py` show this problem. Moreover,
the `cos` can be left out:
{{{
sage: M = sgn((3/2),hold=True); M.n()
---------------------------------------------------------------------------
TypeError Traceback (most recent call
last)
<ipython-input-18-b9940d9ad473> in <module>()
----> 1 M = sgn((Integer(3)/Integer(2)),hold=True); M.n()
/home/ralf/sage/local/lib/python2.7/site-
packages/sage/symbolic/expression.so in
sage.symbolic.expression.Expression._numerical_approx
(build/cythonized/sage/symbolic/expression.cpp:27093)()
TypeError: cannot evaluate symbolic expression numerically
}}}
All the generalized functions have this code in `_eval_()` and I believe
the bug to be there:
{{{
try:
approx_x = ComplexIntervalField()(x)
if bool(approx_x.imag() == 0): # x is real
if bool(approx_x.real() == 0): # x is zero
return ...
else:
return ...
else:
return ... # x is complex
except Exception: # x is symbolic
pass
return None
}}}
--
Ticket URL: <http://trac.sagemath.org/ticket/16587#comment:3>
Sage <http://www.sagemath.org>
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