[eigen] Sign function

[Carlos Becker <carlosbecker@xxxxxxxxx>]

Hello everyone,

I am wondering which would be the fast way to compute the sign of every element in a vector or matrix, since I have to do the following element-wise:

A = A + k * sign(B)

where A and B are double matrices and k is a scalar.

I was trying to find some information in the docs but so far I didn't succeed.

I know I can do a boolean operation and then cast to double, multiply by 2 and subtract 1, but that doesn't seem very efficient.

Maybe some kind of custom element-wise processing, since it would be enough to compute the sign and then add k or -k to each element of A ?

Thanks!