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Blog
Program review for Fitting Equations
June 1, 2008
During a couple of my last postings, I discussed the use and behavior of viscosity data curve fit to a particular equation. A problem exists in that there are few really good curve-fitting programs available to perform the fit with high quality and low cost. I was fortunate to have access to a wonderful program back in 1976 at RPI which Dr. Van Ness gave me. It was very flexible, and I could add any equation into it to perform the fit and used Marquart’s method of steepest decent to find the coefficients, so it was very fast as well. I still have the card deck but cannot use it as there are no card readers and not many FORTRAN compilers which will handle it. So I spent quite a while searching for programs which could handle the nonlinear multiple variables of the viscosity equitation I prefer. There were a few which seemed capable, but they were at least $1,000, which was beyond my means as an individual.
However, after an extended search I came across the POLYMATH program, which you can find at http://www.polymath-software.com The program is compatible with EXCEL and has several solution methods. The Website description is:
“POLYMATH is a proven computational system, which has been specifically created for educational or professional use. The various POLYMATH programs allow the user to apply effective numerical analysis techniques during interactive problem solving on personal computers. Results are presented graphically for easy understanding and for incorporation into papers and reports. Engineers, mathematicians, scientists, students or anyone with a need to solve problems will appreciate the efficiency and speed of problem solution.”
The POLYMATH program was written by:
Mordechai Shacham, Michael B. Cutlip, and Michael Elly. Dr. Shacham is a professor of Chemical Engineering at Ben-Gurion University of the Negev, Dr. Cutlip is a professor of Chemical Engineering at the University of Connecticut, and Michael Elly is a Senior Automation Engineer at Intel Corp.
Purchase price for an individual user is $189 and an educational copy for $39 which I find very reasonable for the value it supplies. Aside from the viscosity work, it can also be used to evaluate the coefficients for designed experiments or any other data which you have taken in your daily work (we are engineers!). It can also solve ordinary differential equations, but I have not used that function yet myself.
I would visit the Website and consider the program. Then as we progress further into the "Secrets of Substrates," we can go over a few examples where we need to fit data a little bit better than Excel can, and you will be able to use the methods discussed in your own work
Posted by Eldridge M. Mount on June 1, 2008 | Comments (0)