sparse_learn/c/head_tail_proj.c
int _comp_descend(const void *a, const void *b) {
    if (((data_pair *) a)->val < ((data_pair *) b)->val) {
        return 1;
    } else {
        return -1;
    }
}
// compare function for descending sorting.
compare function for descending sorting.
compare function for descending sorting .
int _comp_descend(const void *a, const void *b) {
    if (((data_pair *) a)->val < ((data_pair *) b)->val) {
        return 1;
    } else {
        return -1;
    }
}
int _comp_descend ( const void * a , const void * b ) { if ( ( ( data_pair * ) a ) -> val < ( ( data_pair * ) b ) -> val ) { return 1 ; } else { return -1 ; } }
compare function for descending sorting.
compare function for descending sorting .