The closest you can lkikely get is the sigmf (link) function in the Fuzzy Logic Toolbox.
You can easily write your own:
sgn = @(x,a,c) 1./(1 + exp(-a.*(x-c)));
x = 0:0.1:10;
y = sgn(x, 2, 4);
xlabel('sigmf, P = [2 4]')
This plot matches the one in the documentation.
Experiment to get the result you want.