[Numpy-discussion] f.p. powers and masked arrays (original) (raw)
Michael Fitzgerald fitz at astron.berkeley.edu
Thu Jun 22 00:39:51 EDT 2006
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Hello all,
I'm encountering some (relatively new?) behavior with masked arrays that strikes me as bizarre. Raising zero to a floating-point value is triggering a mask to be set, even though the result should be well-defined. When using fixed-point integers for powers, everything works as expected. I'm seeing this with both numarray and numpy. Take the case of 0**1, illustrated below:
import numarray as n1 import numarray.ma as n1ma n1.array(0.)**1 array(0.0) n1.array(0.)**1. array(0.0) n1ma.array(0.)**1 array(0.0) n1ma.array(0.)**1. array(data = [1.0000000200408773e+20], mask = 1, fill_value=[ 1.00000002e+20])
import numpy as n2 import numpy.core.ma as n2ma n2.array(0.)**1 array(0.0) n2.array(0.)**1. array(0.0) n2ma.array(0.)**1 array(0.0) n2ma.array(0.)**1. array(data = 1e+20, mask = True, fill_value=1e+20)
I've been using python v2.3.5 & v.2.4.3, numarray v1.5.1, and numpy v0.9.8, and tested this on an x86 Debian box and a PPC OSX box. It may be the case that this issue has manifested in the past several months, as it's causing a new problem with some of my older code. Any thoughts?
Thanks in advance, Mike
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