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.gif
source.gif
test-new-code-0human-parameters.txt
test-new-code-0lensedimage.gif