[Numpy-discussion] np.finfo().maxexp confusing

Matthew Brett matthew.brett@gmail....
Tue Oct 11 13:39:48 CDT 2011


Hi,

I realize it is probably too late to do anything about this, but:

In [72]: info = np.finfo(np.float32)

In [73]: info.minexp
Out[73]: -126

In [74]: info.maxexp
Out[74]: 128

minexp is correct, in that 2**(-126) is the minimum value for the
exponent part of float32.  But maxexp is not correct, because 2**(127)
is the maximum value for the float32 exponent part:

http://en.wikipedia.org/wiki/Single_precision_floating-point_format

There is the same maxexp+1 feature for the other float types.

Is this a sufficiently quiet corner of the API that it might be
changed in the future with suitable warnings?

Best,

Matthew


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