MATLAB: Curve fitting toolbox

1th derivativecurve fittingCurve Fitting Toolbox

I'm programming in matlab and using curve fitting toolbox to fit my data. I need to evaluate the 1th derivative of my curve in some data point. Do you know how I can do it in my code? I need to use 'cubic spline (interpolant) fitting'.

Best Answer

The curvefit object you get out of curvefitting tool will allow you to take a derivative at a point using the differentiate method.
See code below. I generated a fit using the command line but it is the same thing you can get out of the curvefitting toolbox.
load census
f2 = fit(cdate,pop,'cubicinterp');
fx = differentiate(f2, 0.2)
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