get_openmp_version Function

    function get_openmp_version() result(openmp_version)
        implicit none
        character(:), allocatable :: openmp_version

#ifdef _OPENMP
        select case (_OPENMP)
        case (199911)
            openmp_version = '1.0'
        case (200203)
            openmp_version = '2.0'
        case (200505)
            openmp_version = '2.5'
        case (200805)
            openmp_version = '3.0'
        case (201107)
            openmp_version = '3.1'
        case (201307)
            openmp_version = '4.0'
        case (201511)
            openmp_version = '4.5'
        case (201811)
            openmp_version = '5.0'
        case (202011)
            openmp_version = '5.1'
        case (202111)
            openmp_version = '5.2'
        case default
            openmp_version = 'unknown'
        end select
#else
        openmp_version = 'not defined'
#endif

    end function get_openmp_version