[Numpy-discussion] Piecewise functions.

[Andrea Riciputi]

I've already tried something like this, but it doesn't work since f1  
and f2 return not valid values outside the range over they are  
defined. Perhaps an example could clarify; suppose that f1(x) = 1./ 
sqrt(1 - x**2) for x <= 1, and f2(x) = 1./sqrt(x**2 - 1) for x > 1.

Your suggestion, as the other I've tried, fails with a  
"OverflowError: math range error".

Any helps?
  Andrea.

On Sep 22, 2005, at 9:33 PM, Alan G Isaac wrote:

> On Thu, 22 Sep 2005, Andrea Riciputi apparently wrote:
>
>> this is probably an already discussed problem, but I've not been able
>> to find a solution even after googling a lot.
>>
>
>
>> I've a piecewise defined function:
>>
>
>
>>         /
>>         | f1(x)    if x <= a
>> f(x) = |
>>         | f2(x)    if x > a
>>         \
>>
>
>
>> where f1 and f2 are not defined outside the above range. How can I
>> define such a function in Python in order to apply (map) it to an
>> array ranging from values smaller to values bigger than a?
>>
>
> I suspect I do not understand your question.
> But perhaps you want this:
>
> def f(x):
>     return x<=a and f1(x) or f2(x)
>
> fwiw,
> Alan
>
>
>
>
>
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