Tested each sample.

gem/makefile

@@ -12,3 +12,12 @@ clean:
 
 pdf: ltn012.pdf
 	open ltn012.pdf
+
+test: gem.so
+
+
+gem.o: gem.c
+	gcc -c -o gem.o -Wall -ansi -W -O2 gem.c
+
+gem.so: gem.o
+	export MACOSX_DEPLOYMENT_TARGET="10.3"; gcc -bundle -undefined dynamic_lookup -o gem.so gem.o