[metapost] tangent

[Laurence Finston]

On Mon, 17 Jan 2005, Honza Prachar wrote:

> I meant general curve. I found solution using loop to determine right
> point, where tangent and curve have same direction. But I do not believe
> it is the simpliest solution.
>

This is another situation where one will have to look for solutions on
the basis of individual segments of the curves, i.e., sets of 4
control points where the first and last control points lie on the
curve.  Metafont "just" chains these segments together.
So you're going to have to loop or recurse no matter what.
However, I have every faith that one of the good mathematicians on this
list can give you some hints, and maybe even a canned solution.

Laurence