📌 Fixed openmp check in Makefile.

Makefile

@@ -9,8 +9,11 @@ PROJECTS := $(wildcard $(SRC_DIR)/*)
 BINS := $(patsubst $(SRC_DIR)/%, $(OUT_DIR)/%, $(PROJECTS))
 LIB_SOURCES := $(wildcard $(LIB_DIR)/*.cpp)
 
+# checking with a silly test program whether openmp is accessible
+# maybe at some point a cmake file would be more elegant.
 OPENMP_FLAG :=
-OPENMP_CHECK := $(shell echo | $(CXX) -fopenmp -x c++ - -o /dev/null 2>/dev/null && echo yes)
+OPENMP_CHECK := $(shell printf '#include <omp.h>\nint main(){return 0;}' | \
+	$(CXX) -std=c++23 -fopenmp -x c++ - -o /dev/null 2>/dev/null && echo yes)
 
 ifeq ($(OPENMP_CHECK),yes)
     OPENMP_FLAG := -fopenmp