```/* nag_sort_quicksort (m01csc) Example Program.
*
* Copyright 2019 Numerical Algorithms Group.
*
* Mark 27.0, 2019.
*/

#include <nag.h>
#include <stdio.h>

#ifdef __cplusplus
extern "C"
{
#endif
static Integer NAG_CALL compare(const Nag_Pointer a, const Nag_Pointer b);
#ifdef __cplusplus
}
#endif

#define VEC(I, J) vec[(I) *tdvec + J]
int main(void)
{
Integer exit_status = 0, i, j, k, m, n, tdvec;
double *vec = 0;
NagError fail;

INIT_FAIL(fail);

/* Skip heading in data file */
scanf("%*[^\n]");
printf("nag_sort_quicksort (m01csc) Example Program Results\n");
scanf("%" NAG_IFMT "", &m);
scanf("%" NAG_IFMT "", &n);
scanf("%" NAG_IFMT "", &k);
if (m >= 1 && n >= 1 && k >= 1) {
if (!(vec = NAG_ALLOC(m * n, double)))
{
printf("Allocation failure\n");
exit_status = -1;
goto END;
}
tdvec = n;
}
else {
printf("Invalid m or n or k.\n");
exit_status = 1;
return exit_status;
}
for (i = 0; i < m; ++i)
for (j = 0; j < n; ++j)
scanf("%lf", &VEC(i, j));
/* nag_sort_quicksort (m01csc).
* Quicksort of set of values of arbitrary data type
*/
nag_sort_quicksort((Pointer) &VEC(0, k - 1), (size_t) m, sizeof(double),
(ptrdiff_t) (sizeof(double) * n), compare, Nag_Ascending,
&fail);
if (fail.code != NE_NOERROR) {
printf("Error from nag_sort_quicksort (m01csc).\n%s\n", fail.message);
exit_status = 1;
goto END;
}
printf("\nMatrix with column %" NAG_IFMT " sorted \n", k);
for (i = 0; i < m; ++i) {
for (j = 0; j < n; ++j)
printf(" %8.1f ", VEC(i, j));
printf("\n");
}

END:
NAG_FREE(vec);

return exit_status;
}

static Integer NAG_CALL compare(const Nag_Pointer a, const Nag_Pointer b)
{
double x = *((const double *) a);
double y = *((const double *) b);
return (x < y ? -1 : (x == y ? 0 : 1));
}
```