# Documentation

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# Diff. Sigmoidal MF

Difference of two sigmoids membership function in Simulink software

## Description

The Diff. Sigmoidal MF block implements a membership function in Simulink® based on the difference between two sigmoids. The two sigmoid curves are given by

`${f}_{k}\left(x\right)=\frac{1}{1+\mathrm{exp}\left(-{a}_{k}\left(x-{c}_{k}\right)\right)}$`

where k=1,2. The parameters a1and a2 control the slopes of the left and right curves. The parameters c1 and c2 control the points of inflection for the left and right curves. The parameters a1 and a2 should be positive.