multiple non-linear regression analysis

["Kenlo Nishida" <kenlo(at)ntsg.umt.edu>]

Dear IDL news group:

How can I make multiple non-linear regression analysis with IDL?
I know "LMFIT" command can make a non-linear regression analysis
for a single independent variable. However, I want to know
an appropriate command or function of IDL which provide me with
a fitting of an arbitrary non-linear function with two or more 
independent variables. I mean, I want to determine the following 
three parameters (a, b, c):

y=f(x1, x2, x3; a, b, c)

Here x1, x2, and x3 are arrays of independent variables each
containing n data. y is an array of dependent variable with
n data. a, b, and c are scalars (parameters) which determine 
the non-linear function f(x1, x2, x3).

Kenlo Nishida

Numerical Terradynamic Simulation Group (NTSG)/EOS training Center 
School of Forestry, The University of Montana, Missoula, MT 59812, USA
Office (406) 243-4693; Fax (406) 243-4510
kenlo@ntsg.umt.edu