Define multiple starting points for two-exponential curve fitting (Curve Fitting Toolbox)

Hi,

I have a set of data on which I need to use the two-exponential decay model 'exp2' from the Curve Fitting Toolbox. When I attempted to call the "fit" function ( f=fit(xCol,yCol,'exp2','StartPoint',[maxX,maxY])), MATLAB told me I needed 4 starting points for this model. What is the proper syntax for specifying these? I tried:

f=fit(xCol,yCol,'exp2','StartPoint',[maxX1,maxY1,maxX2,maxY2,maxX3,maxY3,maxX4,maxY4])), but MATLAB told me I had too many start points.

Thanks in advance!

Answer 1

[Adam Danz]

If you're fitting a 2-term exponential model such as

f2(x) = a*exp(b*x) + c*exp(d*x)

you'll need 4 starting points (a,b,c,d). In your examples above, you provide 2 and 8 starting points. Your formatting them correctly into a vector but you just need 4 of them.

For more info, see the section " Fit a Two-Term Exponential Model ".