[pstricks] Drawing S- and Z-Curves

[Rich Shepard]

On Tue, 21 Apr 2009, Michael Sharpe wrote:

> For the bell shaped curve with value 1 at x=m, variance v, plotted
> from x=a to x=b, you could use
> \psplot[algebraic]{a}{b}{Ex(-(x-m)^2/v)}
> where, of course, specific numbers should be substituted for m, v, a, b.

> A similar expression can be constructed for the particular logistic
> curve (S-curve) you need, possibly expressed most simply using \tanh,
> written th in algebraic formulas. Eg
> \psplot[algebraic]{a}{b}{(1+th(x/2))/2}

Michael,

   Yes, these will certainly work. The Z-curve will then be the inverse of
the S-curve. That's what I've done in python, but I did not know the
appropriate PSTricks approach.

Many thanks,

Rich

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