how to take the derivative of the function saved from curve fitting tool

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zein 2021-3-1

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评论： Simon Allosserie 2021-3-3

I want to take the derivative of the following function after extracting the curve fitted from cftool. I have saved the curve fitted curve to my workspace.

I want to know how to get the highest slope (derivate) of the curve with respect to x-data ?

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Simon Allosserie 2021-3-1

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编辑：Simon Allosserie 2021-3-1

在 MATLAB Online 中打开

If you have the values of your fitted curve saved, you can calculate the first derivative by using the gradient function: https://nl.mathworks.com/help/matlab/ref/gradient.html For example

fx = gradient(x) %calculate first derivative of the vector x containing your curve data.

Hope this works :)

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zein 2021-3-3

I used the equation, but the max slope was increasing with decreasing the step until certain limit then the max slope become constant. I think that is normal, right?

Simon Allosserie 2021-3-3

As per the definition of a slope, this is indeed normal. It is literally called "derivatve" because ultimately it determines the slopes over a infinitesimal x-step. So yes, once it converges to a constant value that should be right I think!

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