[epicurus:~/C/ep3]$ ll
total 5
-rw-r--r--   1 yoshi    prof          743 Jun  4 23:36 Makefile
-rw-r--r--   1 yoshi    prof         1423 Jun  4 23:36 gb_flip.c
-rw-r--r--   1 yoshi    prof          170 Jun  4 23:36 gb_flip.h
-rw-r--r--   1 yoshi    prof          486 Jun  4 23:36 test_flip.c
[epicurus:~/C/ep3]$ make test_flip
gcc -g -Wall -I. -c test_flip.c
gcc -g -Wall -I. -c gb_flip.c
gcc -L.  -o test_flip test_flip.o gb_flip.o -lm 
[epicurus:~/C/ep3]$ test_flip 
OK, the gb_flip routines seem to work!
[epicurus:~/C/ep3]$