[pstricks] Drawing S- and Z-Curves

[Michael Sharpe]

On Apr 21, 2009, at 2:44 PM, Rich Shepard wrote:

>  I need to draw S- and Z-curves between specific points on the X- 
> axis (as
> well as normal curves). I assume that \psbezier is the appropriate  
> package
> to use for this, but I've not before had any experience with it. If  
> I want
> the curve to start and end at specific x-values, with y=0.5 (on the  
> range
> 0.0-1.0) at a specific x-value, can I do so?
>
>  There is an example of Bezier curves in Herbert's Chapter 5 of  
> TLGC2 (in
> the section on curves). Is there a more complete description of this
> package?
>
>  What I would like to do is re-draw the Xfig graphics I used in my  
> book
> using PSTricks. One example (term-set.eps) is attached. A pointer on  
> what to
> read to learn how to do figures of this sort with PSTricks will be  
> much
> appreciated.

Both S-curves and Z-curves, as I know them, are defined by functions  
known to Postscript, so there is no need for Bezier approximations. Of  
course, both those terms have multiple meanings, but I assume that Z- 
curve means a normal density curve (two parameters) and S-curve means  
a logistic curve (3 parameters.)

Michael