[drgrice1]

JSXGraph 1.13.0 enables RDPsmoothing by default for functiongraph elements. That thins out the curve points, and since the fill code filters those points to the fill_min/fill_max range, the fill no longer starts at fill_min (or ends at fill_max), leaving a visible gap.

The following MWE can be used to test this.

DOCUMENT();

loadMacros('PGstandard.pl', 'PGML.pl', 'plots.pl', 'PGcourse.pl');

$graph = Plot(xmin => -4, xmax => 4, ymin => 0, ymax => 0.42);
$graph->add_dataset([ [ -1, 0 ], [ -1, exp(-1 / 2) / sqrt(2 * pi) ] ]);
$graph->add_function([
    'exp(-x^2 / 2) / sqrt(2 * pi)', 'x', -4, 4,
    name     => 'f',
    fill     => 'xaxis',
    fill_min => -1,
    fill_max =>  4,
    #jsx_options => { RDPsmoothing => 0 }
]);

BEGIN_PGML
[!graph!]{$graph}
END_PGML

ENDDOCUMENT();

With the develop branch (or the main branch) there is a visible gap on the left side of the fill region. If the commented out line in that code is uncommented, the gap goes away with the develop branch. With this branch the macro adds that option, so the gap also is gone.

[pstaabp]

I'm not seeing a gap on develop. Here's what I'm seeing:

[drgrice1]

Are you sure that you have the line #jsx_options => { RDPsmoothing => 0 } commented out? I see

with that line commented out. If I uncomment that line or use this pull request, then the gap goes away.

[drgrice1]

That happens with the main branch as well by the way.

[pstaabp]

I'm still not seeing it on develop, but am on main and this is pretty straightforward.