Hmmmmm, I tried that and it still does not work right. Now I get:

rc/p53.cc:61: no matching function for call to `Simplexer::Simplexer(
<unknown type>, double)'

And if I put:
Simplexer yoyo(&(Model::least_squares),1e-8);

I get an internal compiler error! Maybe I should try inheritence

Thanks anyhow.