Dumb question: How do you protect it? Mark On Jul 28, 2011, at 3:05 PM, Barry Smith wrote:

On Jul 28, 2011, at 11:55 AM, Jose E. Roman wrote:

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We are getting an undefined reference `MPI_Exscan'. This function is used in src/mat/impls/nest/matnest.c. If I am not wrong, MPI_Exscan was introduced in MPI-2 but was not available in the previous standard. Apparently, the machine where we are compiling is very old and has MPI-1 only.

I guess there should be a PETSC_HAVE_MPI_EXSCAN test in configure.

Correct, whoever used that MPI 2 function in PETSc is obligated to protect it.

Barry

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Jose