[Numpy-discussion] TypeError when using double , longdouble in numpy.dot
Christoph Gohlke
cgohlke at uci.edu
Thu Jul 8 00:13:05 EDT 2010
Dear NumPy developers,
I am trying to solve some scipy.sparse TypeError failures reported in
[1] and reduced them to the following example:
>>> import numpy
>>> a = numpy.array([[1]])
>>> numpy.dot(a.astype('single'), a.astype('longdouble'))
array([[1.0]], dtype=float64)
>>> numpy.dot(a.astype('double'), a.astype('longdouble'))
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: array cannot be safely cast to required type
Is this exception expected?
Also I noticed this:
>>> numpy.array([1]).astype('longdouble').dtype.num
13
>>> numpy.array([1.0]).astype('longdouble').dtype.num
12
I am using Python 2.6.5 for Windows and numpy 1.4.1 compiled with msvc9,
where sizeof(longdouble) == sizeof(double).
[1] http://aspn.activestate.com/ASPN/Mail/Message/scipy-user/3875416
--
Christoph
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