There are a few things that can cause LATEX to stop with an error message when reading an .eepic file written by ePiX. The most common is the appearance of nan (not a number) where LATEX expects a number. This generally indicates division by zero or bad exponentiation.
When a number is very small, ePiX may write it in exponential notation. If this happens, LATEX will pause with an error message when it tries to read, e.g., 1.4142135e-14. This bug in ePiX has been addressed; please send the author a bug report if you encounter this behavior. You can manually edit the .eepic file, replacing underflows with 0. In this eventuality, it's wise to rename the edited file, lest ePiX overwrite your changes the next time you run it.
Overflow errors are possible if a point has coordinates larger
than ; make sure you're not trying to plot the graph of a
pole or something similar.
Occasionally ePiX will not generate any data points after it starts a path; this may signify a variable whose value is not what you expect (particularly in a loop), a badly defined function, or a bug in ePiX. If you cannot resolve the problem, and have narrowed down the issue to a small input file, please send the author a copy of the file and an explanation of the problem.
LATEX has limited memory, and cannot plot arbitrarily many
points. Make sure you did not accidentally append a digit to the
number of points to be plotted; 500 data points should be fine, but
5000 will almost surely cause problems. If necessary, a long list of
data points in a path can be broken into groups of a few
hundred (see fractal, in arcana.cc), but even so
LATEX will eventually overflow. Don't expect to render a bitmap as
an array of colored boxes in LATEX .
One of the benefits of .eepic files is that they're plain text. ePiX comments its output, which should assist you in debugging. Each object or plot command in the input file generates a stanza in the output file that has a label saying which function wrote the stanza.
If a run of ePiX is taking unusually long (more than a few seconds), it's a good idea to kill the process by typing ctrl-C and to inspect the output for signs of an infinite loop. There is output size checking, but conceivably some infinite loop will be missed. On a fast PC, ePiX can easily write 15 MB of data per second, which will quickly fill up your disk and possibly damage other files. Do not run ePiX as root for normal usage!