Double_t fitLambertW(Double_t * x, Double_t *par) { double prefactor = (par[0]*TMath::Power(x[0],par[1])); return prefactor * gsl_sf_lambert_W0( (1e-3)/(par[2]*prefactor) ); }
static VALUE Lambert_W0(VALUE self, VALUE x) { return rb_float_new(gsl_sf_lambert_W0(NUM2DBL(x))); }