Gravitational Lensing
Here is an image made where I changed the code in glellipse to fix the horizontal line problem. An einstein ring was produced from a point source, which gridlines every 20 pixels (1px = 0.38 arcseconds).

File listing:

einsteinring.gif

pointsource-human-parameters.txt

pointsource-parameters.txt

pointsource.gif

source.gif

test-new-code-0human-parameters.txt

test-new-code-0lensedimage.gif

test-new-code-0parameters.txt