Debugging Tutorial

• Good Programming Practices
• Compiler Errors
• Run-Time Errors
• Wrong Answers
• MPI Errors
• Utilities

While programming might be thought of as the process of developing algorithms and implementing them in a particular programming language, any experienced programmer will tell you most of your time won't be spent writing the program; it will be spent debugging the code and verifying the results. Although there exists documentation on how to use specific debugging utilities, there is little in the way of general debugging strategies or how best to implement a particular debugging tool.

This tutorial gives some general advice about debugging a large code for scientific applications. It will focus on using Fortran 90, but much will apply to any debugging problem. It will also address specific issues of concern to NERSC users such as MPI errors and debugging utilities available on NERSC machines.