将S形拟合到数据 [英] Fitting sigmoid to data

问题描述

有很多曲线拟合和插值工具，例如polyfit(甚至我发现的这个不错的logfit工具箱

There are many curve fitting and interpolation tools like polyfit (or even this nice logfit toolbox I found here), but I can't seem to find anything that will fit a sigmoid function to my x-y data.

是否存在这样的工具，或者我需要自己制作一个工具?

Does such a tool exist or do I need to make my own?

推荐答案

如果安装了统计工具箱，则可以使用 nlinfit :

If you have the Statistics Toolbox installed, you can use nonlinear regression with nlinfit:

sigfunc = @(A, x)(A(1) ./ (A(2) + exp(-x)));
A0 = ones(size(A)); %// Initial values fed into the iterative algorithm
A_fit = nlinfit(x, y, sigfunc, A0);

这里sigfunc只是一个S型函数的示例，而A是拟合系数的向量.

Here sigfunc is just an example for a sigmoid function, and A is the vector of the fitting coefficients.

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