This seems likely to be just an oversight on Jpgraph's part of an option which isn't used that much. Here's a spreadsheet showing the different renderings in Excel for each of gap, zero, and span.
33_Chart_create_scatter7_blanks.xlsx
And here are the 3 identical (except for different titles) Jpgraph renderings of those charts.
Not a terribly important problem. If you can see a way to fix it, great! If not, we'll survive.
This seems likely to be just an oversight on Jpgraph's part of an option which isn't used that much. Here's a spreadsheet showing the different renderings in Excel for each of
gap,zero, andspan.33_Chart_create_scatter7_blanks.xlsx
And here are the 3 identical (except for different titles) Jpgraph renderings of those charts.
Not a terribly important problem. If you can see a way to fix it, great! If not, we'll survive.