Please note that the paths for the -I and -L options in the Makefile were set for machines on MathNet, as is the "machines" file. You'll want to use /u/laguna/h1/fa/eijkhout/mpich instead of /u/jacobi/h1/guest/eijkhout in both the -I and -L options in the Makefile, and use a machines file containing the lines:

earth
helios
zuma
venice
laguna

To see my solutions to the second homework, see here. The file "smooth.c" is the source code, while machines and Makefile are the supporting files. Note that to save myself typing, I put the "mpirun" command in the Makefile as a target, so all I needed to do to run the program while testing is "make run".
For additional "fun", see the 110-2.ps file. This is a plot of student output (the crosses), my output (the diamonds), and a true square function (the squares with dots inside).