Hiroyuki Kawakatsu writes: > i tried to test the non-linear least squares routine using the nist > problems http://www.itl.nist.gov/div898/strd/nls/nls_main.shtml but > don't seem to get any accuracy at all. You're right, I've run a couple of the nist tests and there is a bug which prevents convergence for some problems. Thanks. I will fix that.