[metapost] memory problem

[Denis.Roegel at loria.fr]

> I have to look this up to be sure, but I strongly suspect that what
> happens is this: for each new equation, metapost runs through the
> complete list of variables to see if its status has changed thanks to
> the new equation. If you have a lot of 'not known' variables,
> this process can become very slow.

So it's like quadratic in the number of equations, even though
there can be n sets of independent equations:
with say 100 sets of 25 equations, the time would be something
like 100*25*25 if there are never more than 25 equations,
but (100*25)^2 if the equations are solved only at the end,
hence 100 times slower.

If this is so, I wonder if some extension of metapost could 
or should have such a notion of sets of independent equations. 

Denis