Change of bounds for Chebyshev polynomials

I need to change the region of a vector of observations from [-Inf:Inf] to [-1:1] to use with some higher order Chebyshev polynomials.

I know there is a tried and tested little function for doing this. Something like...1/1-exp(x^2.....).

I can't remember what this is. Would someone please be able to post this for me?

Many thanks,

J

You have to find an odd function for which is ... a good candidate is...



Kind regards

It's typical to use one of these guys: Sigmoid function - Wikipedia, the free encyclopedia

Thank you both.