ratfun_gam
yy = ratfun_gam(y - x0, 0);
yy = ratfun_gam(y - x0, 0);
r = ratfun_gam(t, d);
yy = ratfun_gam(y - x0, 0);
yy = ratfun_gam(y - x0, 0);
r = ratfun_gam(t, d);