Optimization of parameters of the sigmoid function
Syntax:
[param]=sigm_fit(x,y)
that is the same that
[param]=sigm_fit(x,y,[],[],[]) % no fixed_params, automatic initial_params
[param]=sigm_fit(x,y,fixed_params) % automatic initial_params
[param]=sigm_fit(x,y,[],initial_params) % use it when the estimation is poor
[param]=sigm_fit(x,y,fixed_params,initial_params,plot_flag)
param = [min, max, x50, slope]
if fixed_params=[NaN, NaN , NaN , NaN] % or fixed_params=[]
optimization of "min", "max", "x50" and "slope" (default)
if fixed_params=[0, 1 , NaN , NaN]
optimization of x50 and slope of a sigmoid of ranging from 0 to 1
Additional information in the second output, STAT
[param,stat]=sigm_fit(x,y,fixed_params,initial_params,plot_flag)
Example:
%% generate data vectors (x and y)
fsigm = @(param,xval) param(1)+(param(2)-param(1))./(1+10.^((param(3)-xval)*param(4)))
param=[0 1 5 1]; % "min", "max", "x50", "slope"
x=0:0.1:10;
y=fsigm(param,x) + 0.1*randn(size(x));
%% standard parameter estimation
[estimated_params]=sigm_fit(x,y)
%% parameter estimation with forced 0.5 fixed min
[estimated_params]=sigm_fit(x,y,[0.5 NaN NaN NaN])
%% parameter estimation without plotting
[estimated_params]=sigm_fit(x,y,[],[],0)
Cite As
R P (2025). sigm_fit (https://www.mathworks.com/matlabcentral/fileexchange/42641-sigm_fit), MATLAB Central File Exchange. Retrieved .
MATLAB Release Compatibility
Platform Compatibility
Windows macOS LinuxCategories
Tags
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!Discover Live Editor
Create scripts with code, output, and formatted text in a single executable document.