forum.alglib.net

I am trying to test the "lsfitlinear" by copy the example from here http://www.alglib.net/translator/man/manual.csharp.html#example_lsfit_d_lin

The documents says:
// * fmatrix - matrix of basis functions calculated at sample points
// Actually, we have only one basis function F0 = exp(0.5*x).


Questions: does that mean user can't change the basis function? If the answer is yes, then how should user use their own defined function?

thanks,