[Numpy-discussion] exp behaviour: is it a bug ?

Czerminski, Ryszard ryszard at arqule.com
Fri Jun 2 10:32:49 CDT 2000


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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