Exercise "debug"

Debug somebody else's project here.

The assignment was the following: "implement a function, print_half_00, that prints half the [0,0] element of a given gsl_matrix".

You shouldn't rewrite the code, you should only correct the errors --- if any --- in the Makefile and the code.

The answer to this exercise should be the correct Makefile and the correct main.c (it's only few lines each).

Hint: you might want to read man 3 printf and find out what it returns.