a code with C language which uses some fortran libraries

It is a simple C programming, I have 4 big (more than 1 million non zero elements with the format of .mtx) sparse matrix (in the matrix market format) which I need to convert them to compress sparse raw format, and then compute a matrix vector multiplication using both formats (market matrix vs compress sparse raw). for reading matrix market formatted files you should use : [login to view URL]~jburkardt/m_src/mm_io/[login to view URL] for conversion between various formats, and also for matrix vector multiplication using different formats you should use: [login to view URL]~saad/software/SPARSKIT/ in the SPARSKIT instead of Matrix Market you can use Coordinate format. Since these libraries are written in FORTRAN, you should know how to call FORTRAN in C code. I need a clear code with some comments for making it clear. Matrices will be given.