* environment variable MPIE_NUM_THREADS now determines number of threads used in parallel regions

* default value of the OMP_NUM_THREADS variable has to be restored at the end of mpie subroutine, since marc also seems to use and change(!) this 
* usage: "export MPIE_NUM_THREADS=<number of threads>" to set variable in shell, then restart mentat and compile with option 3 (at the moment this does only work on ws 6, since all other workstations use compiler option "-save"; this puts all local variables by default in static memory, which is a killer for parallelization!)

code/mpie_cpfem_marc.f90

@@ -202,6 +202,7 @@ subroutine hypela2(&
                       debug_reset
  use mesh, only:      mesh_FEasCP
  use CPFEM, only:     CPFEM_initAll,CPFEM_general,CPFEM_init_done
+ use OMP_LIB
  implicit none
  
 !     ** Start of generated type statements **
@@ -227,7 +228,19 @@ subroutine hypela2(&
  real(pReal), dimension (3,3) :: pstress                                  ! dummy argument for call of cpfem_general (used by mpie_spectral)
  real(pReal), dimension (3,3,3,3) :: dPdF                                 ! dummy argument for call of cpfem_general (used by mpie_spectral)
 
- integer(pInt) computationMode, i, cp_en
+ integer(pInt) computationMode, i, cp_en, &
+               defaultNumThreadsInt, &                                    ! default value stored in environment variable OMP_NUM_THREADS
+               mpieNumThreadsInt                                          ! value stored in environment variable MPIE_NUM_THREADS
+
+ character mpieNumThreadsString
+ 
+ 
+ defaultNumThreadsInt = omp_get_num_threads()                             ! remember default number of available threads defined by environment variable OMP_NUM_THREADS
+ call GetEnv('MPIE_NUM_THREADS',mpieNumThreadsString)                     ! get environment variable MPIE_NUM_THREADS...
+ read(mpieNumThreadsString,'(i2)') mpieNumThreadsInt                      ! ...convert it to integer...
+ if (mpieNumThreadsInt < 1) mpieNumThreadsInt = 1                         ! ...ensure that its at least one...
+ call omp_set_num_threads(mpieNumThreadsInt)                              ! ...and use it as number of threads for parallel execution
+ 
  
  if (.not. CPFEM_init_done) call CPFEM_initAll(t(1),n(1),nn)
 
@@ -322,6 +335,8 @@ subroutine hypela2(&
  s(1:ngens) = stress(1:ngens)*invnrmMandel(1:ngens)
  if(symmetricSolver) d(1:ngens,1:ngens) = 0.5_pReal*(d(1:ngens,1:ngens)+transpose(d(1:ngens,1:ngens)))
 
+ call omp_set_num_threads(defaultNumThreadsInt)                               ! reset number of threads to stored default value
+
  return
  
 end subroutine