[Numpy-discussion] exp behaviour: is it a bug ?
Jon Saenz
jsaenz at wm.lc.ehu.es
Fri Jun 2 11:49:52 EDT 2000
No, it works correctly for me (other Python revision, anyway):
Python 1.5.2 (#3, Sep 27 1999, 15:02:20) [GCC egcs-2.91.66 19990314
(egcs-1.1.2
on linux2
Copyright 1991-1995 Stichting Mathematisch Centrum, Amsterdam
>>> from math import *
>>> x=-706.
>>> while x>-900:
... x=x-1
... print 'x, exp(x) = %g %g' % (x, exp(x))
...
x, exp(x) = -707 8.99086e-308
x, exp(x) = -708 3.30755e-308
x, exp(x) = -709 1.21678e-308
.....
x, exp(x) = -898 0
x, exp(x) = -899 0
x, exp(x) = -900 0
>>>
Jon Saenz. | Tfno: +34 946012470
Depto. Fisica Aplicada II | Fax: +34 944648500
Facultad de Ciencias. \\ Universidad del Pais Vasco \\
Apdo. 644 \\ 48080 - Bilbao \\ SPAIN
On Fri, 2 Jun 2000, Czerminski, Ryszard wrote:
>
> Is the behaviour illustrated below a bug
> or the Python's feature ?
>
> Python 1.5.2 (#4, Mar 3 2000, 15:04:36) [GCC 2.8.1] on irix6
> Copyright 1991-1995 Stichting Mathematisch Centrum, Amsterdam
> >>>
> >>> from math import exp
> >>> x = -706.
> >>> while x > -900:
> ... x = x - 1
> ... print 'x, exp(x) = %g %g' % (x, exp(x))
> ...
> x, exp(x) = -707 8.99086e-308
> x, exp(x) = -708 3.30755e-308
> x, exp(x) = -709 0
> [...]
> x, exp(x) = -745 0
> Traceback (innermost last):
> File "<stdin>", line 3, in ?
> OverflowError: math range error
> >>>
>
> Ryszard Czerminski phone: (781)994-0479
> ArQule, Inc. email:ryszard at arqule.com
> 19 Presidential Way http://www.arqule.com
> Woburn, MA 01801 fax: (781)994-0679
>
>
> -----Original Message-----
> From: Jean-Bernard Addor [mailto:jbaddor at physics.mcgill.ca]
> Sent: Friday, June 02, 2000 10:19 AM
> To: Numpy-discussion at lists.sourceforge.net
> Subject: [Numpy-discussion] Is it a bug ?
>
>
> Hey Numeric people!
>
> I am just upgrading to a more recent version of Numeric and observe a new
> behaviour:
>
> Python 1.5.2 (#9, May 30 2000, 15:08:12) [GCC 2.95.2 19991024 (release)]
> on linux2
> Copyright 1991-1995 Stichting Mathematisch Centrum, Amsterdam
> Hello from .pythonrc.py
> >>> import Numeric
> >>> Numeric.__version__
> '11'
> >>> Numeric.arange(2)*1j
> Segmentation fault
>
> Python 1.5.1 (#1, Dec 17 1998, 20:58:15) [GCC 2.7.2.3] on linux2
> Copyright 1991-1995 Stichting Mathematisch Centrum, Amsterdam
> Hello from .pythonrc.py
> >>> import Numeric
> >>> Numeric.__version__
> '1.7'
> >>> Numeric.arange(2)*1j
> array([ 0.+0.j, 0.+1.j])
>
> I also saw:
> Numerical Python - Bug Tracking
> Viewing Open Bugs
> Bug ID
> Summary
> 102277
> CFLOAT/DOUBLE_setitem crashes when accessing imag.
> part
>
> Am I hitting that bug?
>
> CU
>
> Jean-Bernard
>
>
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