add some helpful comments about the omp accumulator arrays

Makefile.in

@@ -67,7 +67,7 @@ MODULES = read_input gamma hybrid_update measure_gauge_action start \
 	little_D block Dov_psi operator poly_monomial measurements pion_norm Dov_proj \
 	xchange_field_tslice temporalgauge spinor_fft X_psi P_M_eta \
 	xchange_jacobi jacobi init_jacobi_field \
-	fatal_error invert_clover_eo gettime @SPI_FILES@ init_omp_kahan_accumulators
+	fatal_error invert_clover_eo gettime @SPI_FILES@ init_omp_accumulators
 
 ## the GPU modules (all .cu files in $GPUDIR)
 GPUSOURCES := $(wildcard $(srcdir)/$(GPUDIR)/*.cu)

init_omp_accumulators.h

@@ -16,6 +16,18 @@
  * You should have received a copy of the GNU General Public License
  * along with tmLQCD.  If not, see <http://www.gnu.org/licenses/>.
  ***********************************************************************/
+
+/* The two arrays 
+ *
+ *   g_omp_acc_re
+ *   g_omp_acc_cp
+ *
+ * have as many elements as there are threads (set by ompnumthreads input parameter,
+ * stored in omp_num_threads configuration variable). They are initialiazed
+ * upon program launch and serve to hold thread-local values over the boundaries
+ * of parallel sections, such as for Kahan summations. _re is of type
+ * "double" while _cp is of type "_Complex double". They are declared in global.h */
+
 #ifndef _INIT_OMP_ACCUMULATORS_H
 #define _INIT_OMP_ACCUMULATORS_H