CODEWITHSUNDEEP
fortranopenmpgfortran
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Reputation: 25

Unclassifiable OpenMP directive in a Fortran program

I was trying to parallelize a code in Fortran using openMP, with this code:

program pigreco
    !----------------------------------------!
    use OMP_LIB
    implicit none
    !----------------------------------------!
    integer :: i
    integer, parameter :: N = 100000
    integer, parameter :: NCPU = 4 
    real*8 :: t0, t1 
    real :: h, totale, x, f
    !----------------------------------------!
    print '(a,2x,i15)', ' Number of intervals: ', N
    totale = 0.0
    h = 1. / N

    call OMP_SET_NUM_THREADS(NCPU)
    write(*, '(a,i10)') 'Numero di processori totali: ', NCPU

    t0 = OMP_GET_WTIME()
    !----------------------------------------!
#ifdef PARALLEL
    !
    print '(a)', "Scelta la versione parallela."
    !
    !$OMP PARALLEL DO PRIVATE(x, f) REDUCTION(+:totale)
    !
    do i = 1, N 
        x = (i - 0.5) * h
        f = (4 * h) / (1 + x**2)
        totale = totale + f
    enddo
    !$OMP END PARALLEL DO
    !
#endif
    !
    t1 = OMP_GET_WTIME()
    !
    PRINT '(a,2x,f30.25)', ' Computed PI =', totale
    PRINT '(a,2x,f30.25)', ' Total computational time =', t1 - t0
    !
end program pigreco

When I then try to compile with the line: gfortran prova.F90 -fopenmp -D PARALLEL it gives me an error that says "unclassifiable OpenMP directive at (1)".

Upvotes: 0

Views: 1007

Answers (1)

Javier Garcia
Javier Garcia

Reputation: 578

The problem is that you defined PARALLEL with the preprocessor, so instead of reading OMP PARALLEL DO, the compiler reads OMP 1 DO, which of course doesn't make sense. Change #ifdef PARALLEL to #ifdef RUNPARALLEL and -DPARALLEL to -DRUNPARALLEL, then the compiler gives no error.

Alternatively, you can use the fact that when compiling with OpenMP support the macro variable _OPENMP is defined automatically, so you could use #ifdef _OPENMP, and no -D flag.

Upvotes: 3

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