numpy-discussion

[Numpy-discussion] PS: underflow array([2.9e-131+0j])**3 (why complex give a different result? bug?)

[Jean-Bernard A. <jb...@ph...>]

Hey Numpy people!

This a PS from my previous message. I just tried the underflow with
complex :

>>> Numeric.array([2.9e-131])**3
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
OverflowError: math range error
>>> 2.9e-131**3
0.0
>>> Numeric.array([2.9e-131+0j])**3
array([ 0.+0.j])

Now I have a quick solution for my problem, but I have the impression that
this is a bug, at least I don't understand the underlying logic. If
somebody can explain it to me?

	Jean-Bernard

Re: [Numpy-discussion] PS: underflow array([2.9e-131+0j])**3 (why complex give a different result? bug?)

[Konrad H. <hi...@cn...>]

> >>> Numeric.array([2.9e-131])**3
> Traceback (most recent call last):
>   File "<stdin>", line 1, in ?
> OverflowError: math range error
> >>> 2.9e-131**3
> 0.0
> >>> Numeric.array([2.9e-131+0j])**3
> array([ 0.+0.j])
> 
> Now I have a quick solution for my problem, but I have the impression that
> this is a bug, at least I don't understand the underlying logic. If
> somebody can explain it to me?

The power calculation routines for float and complex are completely
different, I suppose the absence of underflow reporting in the latter
is just a side effect.

Konrad.
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