MATLAB: How to limit variable range with cftool interactive curve fitting toolbox

cftoolcurve fittingrange

I am trying to use cftool to model experimental data using a given theoretical equation to calculate the two unknown parameters. I can input everything and insert the custom equation but I don't know how to force the tool to have a range of x from 0 to infinity and yo from 0 to infinity instead of both being infinity to infinity. The experimental variables cannot be negative numbers. I don't need bounds around the calculated coefficients however.

Best Answer

A quick look at the FITOPTIONS function gives the answer.
Both the linear and nonlinear least squares methods allow lower and upper bounds to be placed on your parameters.
help fitoptions
Were this NOT an option, then you could still solve the problem simply by squaring that parameter inside your model. Until the supreme court has ruled against this, the square of a number is always positive. They might do so though any day now, so beware. :)
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