We have added "-qopenmp" to the compilation and linking commands for a serial code, and numerical results changed slightly. That is, there are no OpenMP pragmas in the code, no OpenMP support functions, and omp.h is not included, but the results are slightly different. I need to track down the cause of the changes.
Can anybody please advise what other compiler arguments -qopenmp sets? I want to experiment with enabling/disabling some of these arguments to find the cause of the difference.