How do I hold a subset of parameters constant in NLINFIT within Statistics Toolbox 5.9 (R2006b)?

Question

MathWorks Support Team am 27 Jun. 2009

I have several parameters to fit using NLINFIT. However, sometimes I would like to fix a subset of the parameters to user-specified values.

Answer 1

MathWorks Support Team am 27 Jun. 2009

An example showing how to fix a subset of parameters using NLINFIT follows:

1. Please download the file 'nlinfitsome.m' to your work directory.

2. Following is an example illustrating the use of NLINFITSOME:

load reaction
betafit = nlinfit(reactants,rate,@hougen,beta)
betafit1 = nlinfitsome([true false false true false],reactants,rate,@hougen,beta)

Notice that parameters 1 and 4 of 'betafit1' are fixed, as shown by comparing the initial parameters beta with betafit1:

 betafit1 =
     1.0000    0.0509    0.0297    0.1000    1.5519
 >> beta
 beta =
     1.0000
     0.0500
     0.0200
     0.1000
     2.0000