Hi Niels,
for constraining, you need a UserFunction, then you don't need to modify
the CurveFitter. Here is an example for a linear fit, where you restrict
the slope
Class ... implements UserFunction
public double userFunction(double[] params, double x) {
if (params[1] > 5 || params[1] < -5) return Double.NaN;
else return params[0] + x*params[1]; //usual linear function
}
CurveFitter cv = new CurveFitter(xData, yData);
cv.doCustomFit(this, /*numParams=*/2, "y=a+b*x constrained",
/*initialParams=*/ null, /*initialParamVariations=*/null,
/*showSettings=*/false);
For best convergence, specify the setOffsetMultiplySlopeParams if
possible, but not for parameters with restricted range.
Michael
________________________________________________________________
On 04.02.21 16:02, NielsMimetas wrote:
> Hi all,
>
> I'm using the curve fitting plugin and want to add constraints to my
> variables.
> For example, lets say that the a-variable can only go from -5 to +5. How
> would I do this?
> I already have the source code of the Curve fitting open, so I can make
> adjustments to the code, I'm just not sure where.
>
> I read a comment from Michael Schmid, who said the following:
> /concerning (1), restricting parameter ranges:
> You can have a function that returns NaN if the parameter enters an
> invalid range. Then the CurveFitter will avoid this range.
> Convergence will be rather bad if the best fit lies very close to a 'NaN
> boundary', however./
> Link:
>
http://imagej.1557.x6.nabble.com/fitting-y-f-x-data-to-arbitrary-functions-in-ImageJ-tp5020273p5020312.html>
> Can someone explain how I would go about this? Where would this function be
> called from? Where in the original code are these parameters requested and
> thus need the NaN be returned?
>
> Thanks in advance,
>
> Niels
>
>
>
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