for Debugging Scientific Applications

ARGE scientific codes are constantly evolving. Refine-ments in understanding physical phenomena result in changes to physics, improved numerical methods result in changes to solution techniques, and developments in computer architecture result in new algorithms. Unfor-tunately, this evolutionary process often introduces sub-tle errors that can be extremely difficult to find. As a consequence, scientific programmers can spend many hours, days, or weeks laboriously comparing the executions of two almost identical codes, seeking to identify the source of a small discrepancy. Debuggers assist in locating program errors. They are tools that allow a user to investigate the execution state of an application program, by (for example) examining the state D a v i d A b r a m s o n, I a n F o s t e r