Least squares for inverse functions

[leastsquaresprogrammer]

Hello, can anyone give some advice or point me to some good pages to solve this type of problem? I want to find the least squares fit of problems with multiplications and inverses.

Specifically I want to find the least squares fit for
y=a/(b+(x-c)) so there are three parameters a,b,c that I want to solve for.

The problem I get is that when I differentiate the sum(error^2) expression and set derivates to zero, I get 2/3 of the equations the same, and I'm stuck from there.

Thanks in advance for any help!
Mark

 

[royhaas]

There are only two parameters in your model. Since \(\displaystyle y = a/(b+(x-c))\) can be written as \(\displaystyle y = a/(x+d)\), you can't separate the two parameters in the denominator.