Using NonlinearFit/Regress?
- To: mathgroup at smc.vnet.net
- Subject: [mg33856] Using NonlinearFit/Regress?
- From: redrooz at yahoo.com
- Date: Sat, 20 Apr 2002 02:49:45 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
I am trying to estimate the parameters {a,b} in the
function: x / (1 + a (x-1) + a b x (x-1)) using
NonlinearFit[...].
The model is known to be a CONCAVE function with
0 < a,b < 1 and b < a. NonlinearFit/Regress
always produces negative parameters (a discontinuous
function); even if I try to condition them to be
positive e.g., {a, 0, 1} and {b, 0, 1}.
Any suggestions about using NonlinearFit[...] with the
above function?
--njg