[pstricks] Ending a psline on pscircle

[Herbert Voss]

Am 12.02.2014 18:30, schrieb Rich Shepard:

>    When I draw a \psline from a point (whose coordinates I know from the
> grid
> and center of the \pscircle or \pselipse) to the boundary line of the
> \pscircle or \pselipse I end up tweaking the terminal coordinates until the
> line end (or terminal arrow point) just touches the boundary line. I'm
> certain there's a method to determining just what those terminal
> coordinates

Rich,
I suppose you are looking for something like that


\documentclass{minimal}
\usepackage{pstricks-add}
\begin{document}

\begin{pspicture}[showgrid](0,3)(10,10)
  \psdot(2,4)\pscircle(7,7){2}
  \psCircleTangents(2,4)(7,7){2}
  \pcline[nodesep=-1cm,linecolor=blue](2,4)(CircleT1)
  \pcline[nodesep=-1cm,linecolor=blue](2,4)(CircleT2)
  \psdots(CircleT1)(CircleT2)
  \uput[-80](CircleT1){T1}\uput[115](CircleT2){T2}
\end{pspicture}

\end{document}


There is also a \psEllipseTangents(x0 , y0)(a, b)(xp, yp)


Herbert