fitting a curve by adjusting exponents
- Subject: [mg3254] fitting a curve by adjusting exponents
- From: wself at viking.emcmt.edu (Will Self)
- Date: 21 Feb 1996 09:35:05 -0600
- Approved: usenet@wri.com
- Distribution: local
- Newsgroups: wri.mathgroup
- Organization: Wolfram Research, Inc.
- Sender: daemon at wri.com
I'm sorry, I lost the original post. Someone wanted to fit a function of the form func[x,y,z,w] = a x^b + c y^d + e z^f + g w^h to some data points. Here's what I would suggest. Write the usual expression ERR for the sum of the squares of the errors. Calculate the gradient of ERR with respect to the 8 variables a through h. Starting with your best guess (from your physics) as to the actual values of the variables, do a gradient search to minimize the total error. In doing the gradient search, you might as well go ahead at each step and minimize ERR + t*grad[ERR] as a function of t. Will Self