#10774: RuntimeError message for numerical infinite loop is printed, not thrown
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Reporter: niles | Owner: jason, jkantor
Type: defect | Status: new
Priority: major | Milestone:
Component: numerical | Keywords: RuntimeError numerics recursion-depth
Author: | Upstream: N/A
Reviewer: | Merged:
Work_issues: |
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Comment(by nbruin):
This is probably a python exception that occurs in a cython routine that
does have any means to report the exception (see
http://docs.cython.org/src/userguide/language_basics.html ) further up.
This example illustrates the behaviour:
{{{
%cython
def error_raiser():
raise RuntimeError, "my error"
cdef int unreportable_error_producer():
error_raiser()
return 1
cdef int reportable_error_producer() except -1:
error_raiser()
return 1
def call_this(reportable=0):
if reportable:
return reportable_error_producer()
else:
return unreportable_error_producer()
}}}
which results in
{{{
sage: call_this(reportable=1)
Traceback (most recent call last):
...
RuntimeError: my error
sage: call_this()
Exception RuntimeError: 'my error' in '[...]unreportable_error_producer'
ignored
0
}}}
The 0 return value there is rather arbitrary, I assume.
You can investigate the errors that arise a little easier by calling:
{{{
sys.setrecursionlimit(100)
N(log(NaN))
log(arcsin(e)).n()
}}}
The traceback clearly shows a ping-pong between
sage.rings.real_mpfr.RealNumber.log and
sage.rings.complex_number.ComplexNumber.log so that's the real source of
the error. It looks like a cython routine involved in creating the
corresponding error object subsequently gets bitten by the already
exhausted recursion depth and has no way of propagating that exception up.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/10774#comment:1>
Sage <http://www.sagemath.org>
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