[pstricks] Using ps code in psplot's limits

[Hubert Lam]

Alan Ristow wrote:
> Hubert Lam wrote:
>> Given that the usage of \psplot (excluding options) is
>>
>> \psplot{x_min}{x_max}{PS code for function}
>>
>>
>> is there a mechanism that I'm not aware of that will allow the effects 
>> of this:
>>
>> \usepackage{pstricks,pst-math}
>> \def\PiFour{PI 4 div}
>> \psplot{0}{\PiFour}{x SIN}
> 
> Yes. I suppose there's more than one way to do it, but the way I would 
> do this is (untested):

Thank you gentlemen -- Jurgen's way is correct. That will make life MUCH 
easier now! :)

Perhaps for the next example of the pstricks user manual might have more 
  examples on using PostScript code? I'm happy to contribute especially 
with things like

\def\Func{x COS}
\psdot(!4 PI mul 7 div /x 4 PI mul 7 div def \Func)

where the dot is created at (4pi/7, cos(4pi/7)). This I learnt from 
looking at one of Herbert Voss' examples on tug.org/pstricks and would 
be helpful to teachers/academics who are drawing curves.