[pstricks] Re: Hyperbolas

[Jacques L'helgoualc'h]

Herbert Voss a écrit, lundi 7 février 2005, à 16:08 :
> [...] However, the definitions should be outside
> of parametricplot

Thanks for this tip; is the following code OK?

\makeatletter
\def\psthyperbola{\pst at object{psthyperbola}}
\def\psthyperbola at i#1#2{%
  \pst at killglue
  \begingroup
  \use at par
  \psthyperbola at ii{#1}{#2}
  \psthyperbola at ii{#1 neg}{#2}% second branch
  \endgroup
}
\def\psthyperbola at ii#1#2{% a b
  \addto at pscode{%
    /a {#1} bind def
    /b #2 def
    /d {1 t dup mul sub} bind def }
  \parametricplot{-.99}{.99}{%
    a t dup mul 1 add d div mul
    b t 2 mul d div mul}
}
\makeatother

-- 
Jacques L'helgoualc'h