EinsteinExact: Don't create *.out file until Kranc has finished succe…

…ssfully

m/Makefile

@@ -1,6 +1,12 @@
 all: EinsteinExact.out
+# Don't create a *.out file until Kranc has finished successfully.
+# This way, one can simply re-run "make" when Kranc is interrupted or
+# reports an error.
 %.out: %.m Metrics/*.m Metrics/*/*.m
-	../../Kranc/Bin/kranc $*.m 2>&1 && (cd .. && git apply m/docfix.patch) | tee $*.out
+	rm -f $*.out
+	{ ../../Kranc/Bin/kranc $*.m &&					\
+	  (cd .. && git apply m/docfix.patch); } 2>&1 | tee $*.err &&	\
+	mv $*.err $*.out
 clean:
-	rm -f EinsteinExact.out
+	rm -f EinsteinExact.out EinsteinExact.err
 .PHONY: all clean