[Numpy-discussion] What is the logical value of nan?

[Lou Pecora]

--- On Wed, 3/11/09, Bruce Southey <bsouthey@gmail.com> wrote:

> From: Bruce Southey <bsouthey@gmail.com>
> Subject: Re: [Numpy-discussion] What is the logical value of nan?
> To: "Discussion of Numerical Python" <numpy-discussion@scipy.org>
> Date: Wednesday, March 11, 2009, 10:24 AM
>
> This is one link that shows the different representation of
> these 
> numbers in IEEE 754:
> http://www.psc.edu/general/software/packages/ieee/ieee.php
> It is a little clearer than Wikipedia:
> http://en.wikipedia.org/wiki/IEEE_754-1985

Thanks.  Useful sites.

> Numpy's nan/NaN/NAN, inf/Inf/PINF, and NINF are not
> nothing so not zero. 

Agreed.  +1

> Also, I think that conversion to an integer should be an
> error for all of these because there is no equivalent 
> representation of these floating 
> point numbers as integers and I think that using zero for
> NaN is wrong.

Another  +1

> Now for the other two special representations, I would
> presume that 
> Numpy's PZERO (positive zero) and NZERO (negative zero)
> are treated as 
> nothing. Conversion to integer for these should be zero.

Yet another  +1.

-- Lou Pecora,   my views are my own.