[MATRIX-SIG] -3**(-1/3.), sgn()

[Jean-Bernard ADDOR]

What I meant was :

def sgn(a):
  return 2*Numeric.greater_equal(a,0) - 1

I don't know which one is better (faster, without using too much memory).
Your give sgn(0)=0 what is better that sgn(0)=1 for mine, but for my
application it doesn't change anythink.

	Jean-Bernard


On Thu, 24 Jul 1997, Timothy A. Hochberg wrote:

> On Thu, 24 Jul 1997, Jean-Bernard ADDOR wrote:
> 
> > I would like to write sgn(a)*abs(a)**(-1/3.) but the sgn function seems
> > not to be defined in python (perhaps because it is not in c, but it is in
> > fortran). I can use greater_equal. Do you have a better solution ?
> 
> For what it's worth, sgn(x) can be implemented as:
> 
> def sgn(x):
>    return greater_equal(x,0) - less_equal(x,0)
> 
> (or is that what you meant by use greater equal?)
> 
>  ____   
>   /im  
> 
> +------------------------------------------------+
> |Tim Hochberg            Research Assistant      |
> |hochberg <at> wwa.com   University of Illinois  |
> |                        Electrical Engineering  |
> +------------------------------------------------+
> 
> 


_______________
MATRIX-SIG  - SIG on Matrix Math for Python

send messages to: matrix-sig@python.org
administrivia to: matrix-sig-request@python.org
_______________