[Numpy-discussion] Piecewise functions.

[Andrea Riciputi]

On Sep 23, 2005, at 5:23 AM, Greg Ewing wrote:

> I wish people would stop suggesting the 'a and b or c' trick,
> because it DOESN'T WORK except in special circumstances (i.e.
> when you can be sure that b is never false).
>
> What you want is:
>
>   def f(x):
>     if x <= a:
>       return f1(x)
>     else:
>       return f2(x)

It doesn't work either. As I've already explained x is an array  
containing values both above and below a!

What I really need is a way to prevent f1 and f2 from acting on those  
values of the 'x' array for which the functions are not defined.

Any other hints?
  Andrea.