Re: postscript dash patterns in parametric vs data plots

[sfeam (E. Merritt) <eam...@gm...>]

On Monday 29 March 2010, Mojca Miklavec wrote:
> PS: if it's only about the round-off error - why not putting some
> "lineto" statements every now and then instead of rlineto? I guess
> rlineto result in smaller files, but one doesn't need to "stroke" the
> line in the middle of curve.

That would work to overcome the current problem.  But according to
the comments in post.trm this runs into a separate problem:

    /* Ghostscript has a "pile-up of rounding errors" bug: a sequence of many
     * rmove's or rlineto's does not yield the same line as move's or lineto's.
     * Therefore, we periodically force an update of the absolute position.
     * There was a case when 400 rlineto's were too much, so let's go a little
     * bit higher than the default function sampling rate in gnuplot.
     * This runs into a second ghostscript bug, that mixing relative and absolute
     * lineto with no intervening 'stroke' is ridiculously slow to render.
     * So we stroke the partial line, update the position in absolute terms,
     * then continue.  This whole section can go away if ghostscript/gv is fixed.
     */
#   define MAX_REL_PATHLEN 105
    if (ps_path_count >= MAX_REL_PATHLEN) {
        fprintf(gppsfile, "stroke %d %d M\n", x, y);
        ps_path_count = 1;
    }

I suppose we could make MAX_REL_PATHLEN configurable, and skip the section if
it is set to zero.

So, has ghostscript/gv been fixed during the intervening years? 
I don't know.