psigmf compute the product of two sigmoidal member
function of x with parameters [a,b,c,d].
Examples
x=linspace(0,1,100)';y1=psigmf(x,[150.1150.3]);y2=psigmf(x,[-150.5-150.7]);y3=psigmf(x,[150.5-150.7]);scf();clf();plot2d(x,[y1y2y3],leg="y1@y2@y3");xtitle("Trapezoidal Member Function Example","x","mu(x)");