From: Rajiv Singh on
See nonlinear grey box modeling feature in System Identification Toolbox.
Basically, you can write a MATLAB file containing your equations and use it
to create what is called a "grey box model". This model then lets you define
parameters and estimate their values using data. See:

http://www.mathworks.com/access/helpdesk/help/toolbox/ident/ug/bq4gq5r-1.html

Also see various demos on this topic under the section "
Tutorials on Nonlinear Grey Box Model Identification
" on system identification product page(demo section):
http://www.mathworks.com/products/sysid/demos.html

Rajiv

"Marcio Barbalho" <marciobarbalho(a)yahoo.com> wrote in message
news:hjv474$55q$1(a)fred.mathworks.com...
> Could you please give more details on how to create this code?
>
> Many thanks


From: Marcus M. Edvall on
Dear Marco,

Take a look at this example: http://tomdyn.com/examples/marinePopulation.html

You could do something similar to that.

Best wishes, Marcus
Tomlab Optimization Inc.
http://tomopt.com/
http://tomsym.com/