# Solver question

• From: Jim Martin <jim martin utah edu>
• To: "gnumeric-list gnome org" <gnumeric-list gnome org>
• Subject: Solver question
• Date: Sun, 22 Mar 2009 16:15:07 -0600

```Hello All:

I have a question about using Solver in Gnumeric (and it seems the same question may apply to OpenOffice
Calc).

Background: I use excel a lot. Probably should have bitten the bullet years ago and learned matlab for the
kinds of things I do (biomechanics research) but so far excel has not let me down in terms of being able to
get things done. It is probably slower than matlab but I like being able to work in a spreadsheet format
rather than command line.  In the spreadsheets that I use, I often use solver to determine regression
coefficients and other terms by minimizing the sum of squared error term between the raw data and the modeled
value. That is, I write a model equation with coefficients located in a few cells. I then calculate the error
term (raw - model values) for each data point. Squaring and summing those terms gives me a sum of squared
error term. In excel, I can use solver to determine the coefficients by minimizing the sum or squared error
term. This ability is very important to many of my applications and I can't do without it.

I was surprised that I could not seem to accomplish this simple task in OpenOffice or in Gnumeric.  In
it (although I am not sure this is true). The trouble is that I do not have constraints in my models (can
can't imagine how I would add them and yes I did take linear algebra years ago). The solver box in excel also
has a box for constraints similar to that in Gnumeric but my technique works fine with no constraints.
Besides using the excel spreadsheets I have built in excel, I have also tried this in Gnumeric using a very
simple linear equation and cannot get a solution. Can someone either tell me the trick to get this to work in
Gnumeric and OpenOffice or explain to my why it can't be done?

The reason for my recently renewed interest in Gnumeric and OpenOffice is that I just wrote a tutorial for
the online journal "Sports Science" in which used excel to determine Fourrier coefficients. A downloadable
spreadsheet is part of the publication.  I would have liked to have been able to upload a free software
version of the spreadsheet but this step kept me from doing so.