If or function pointers in fortran

Question

as it is so common with Fortran, I\'m writing a massively parallel scientific code. In the beginning of my code I read my configuration file which tells me which type of solver

Answer 1

After a brief search I couldn't find the answer to the question, so I ran a little benchmark myself (see this link for the Makefile & dependencies). The benchmark consists of:

• Draw random number to select method a, b, or c, which all perform a simple addition to their single integer argument
• Call the chosen method 100 million times, using either a procedure pointer or if-statements
• Repeat the above 5 times

The result with gfortran 4.8.5 on an CPU E5-2630 v3 @ 2.40GHz is:

Time per call (proc. pointer):       1.89 ns
Time per call (if statement):        1.89 ns

In other words, there is not much of a performance difference!