```/* nag_dpprfs (f07ghc) Example Program.
*
* Copyright 2014 Numerical Algorithms Group.
*
* Mark 7, 2001.
*/

#include <stdio.h>
#include <nag.h>
#include <nag_stdlib.h>
#include <nagf07.h>
#include <nagx04.h>

int main(void)
{
/* Scalars */
Integer       i, j, n, nrhs, ap_len, afp_len, pdb, pdx, ferr_len, berr_len;
Integer       exit_status = 0;
NagError      fail;
Nag_UploType  uplo;
Nag_OrderType order;
/* Arrays */
char          nag_enum_arg;
double        *afp = 0, *ap = 0, *b = 0, *berr = 0, *ferr = 0, *x = 0;

#ifdef NAG_COLUMN_MAJOR
#define A_UPPER(I, J) ap[J*(J-1)/2 + I - 1]
#define A_LOWER(I, J) ap[(2*n-J)*(J-1)/2 + I - 1]
#define B(I, J)       b[(J-1)*pdb + I - 1]
#define X(I, J)       x[(J-1)*pdx + I - 1]
order = Nag_ColMajor;
#else
#define A_LOWER(I, J) ap[I*(I-1)/2 + J - 1]
#define A_UPPER(I, J) ap[(2*n-I)*(I-1)/2 + J - 1]
#define B(I, J)       b[(I-1)*pdb + J - 1]
#define X(I, J)       x[(I-1)*pdx + J - 1]
order = Nag_RowMajor;
#endif

INIT_FAIL(fail);

printf("nag_dpprfs (f07ghc) Example Program Results\n\n");
/* Skip heading in data file */
scanf("%*[^\n] ");
scanf("%ld%ld%*[^\n] ", &n, &nrhs);
ap_len = n * (n + 1)/2;
afp_len = n * (n + 1)/2;
#ifdef NAG_COLUMN_MAJOR
pdb = n;
pdx = n;
#else
pdb = nrhs;
pdx = nrhs;
#endif

ferr_len = nrhs;
berr_len = nrhs;

/* Allocate memory */
if (!(afp = NAG_ALLOC(ap_len, double)) ||
!(ap = NAG_ALLOC(afp_len, double)) ||
!(b = NAG_ALLOC(n * nrhs, double)) ||
!(berr = NAG_ALLOC(berr_len, double)) ||
!(ferr = NAG_ALLOC(ferr_len, double)) ||
!(x = NAG_ALLOC(n * nrhs, double)))
{
printf("Allocation failure\n");
exit_status = -1;
goto END;
}

/* Read A and B from data file, and copy A to AFP and B to X */
scanf(" %39s%*[^\n] ", nag_enum_arg);
/* nag_enum_name_to_value (x04nac).
* Converts NAG enum member name to value
*/
uplo = (Nag_UploType) nag_enum_name_to_value(nag_enum_arg);

if (uplo == Nag_Upper)
{
for (i = 1; i <= n; ++i)
{
for (j = i; j <= n; ++j)
scanf("%lf", &A_UPPER(i, j));
}
scanf("%*[^\n] ");
}
else
{
for (i = 1; i <= n; ++i)
{
for (j = 1; j <= i; ++j)
scanf("%lf", &A_LOWER(i, j));
}
scanf("%*[^\n] ");
}
for (i = 1; i <= n; ++i)
{
for (j = 1; j <= nrhs; ++j)
scanf("%lf", &B(i, j));
}
scanf("%*[^\n] ");
for (i = 0; i < n * (n + 1) / 2; ++i)
afp[i] = ap[i];
for (i = 1; i <= n; ++i)
{
for (j = 1; j <= nrhs; ++j)
X(i, j) = B(i, j);
}
/* Factorize A in the array AFP */
/* nag_dpptrf (f07gdc).
* Cholesky factorization of real symmetric
* positive-definite matrix, packed storage
*/
nag_dpptrf(order, uplo, n, afp, &fail);
if (fail.code != NE_NOERROR)
{
printf("Error from nag_dpptrf (f07gdc).\n%s\n", fail.message);
exit_status = 1;
goto END;
}
/* Compute solution in the array X */
/* nag_dpptrs (f07gec).
* Solution of real symmetric positive-definite system of
* linear equations, multiple right-hand sides, matrix
* already factorized by nag_dpptrf (f07gdc), packed storage
*/
nag_dpptrs(order, uplo, n, nrhs, afp, x, pdx, &fail);
if (fail.code != NE_NOERROR)
{
printf("Error from nag_dpptrs (f07gec).\n%s\n", fail.message);
exit_status = 1;
goto END;
}
/* Improve solution, and compute backward errors and */
/* estimated bounds on the forward errors */
/* nag_dpprfs (f07ghc).
* Refined solution with error bounds of real symmetric
* positive-definite system of linear equations, multiple
* right-hand sides, packed storage
*/
nag_dpprfs(order, uplo, n, nrhs, ap, afp, b, pdb, x, pdx, ferr, berr,
&fail);
if (fail.code != NE_NOERROR)
{
printf("Error from nag_dpprfs (f07ghc).\n%s\n", fail.message);
exit_status = 1;
goto END;
}
/* Print solution */
/* nag_gen_real_mat_print (x04cac).
* Print real general matrix (easy-to-use)
*/
fflush(stdout);
nag_gen_real_mat_print(order, Nag_GeneralMatrix, Nag_NonUnitDiag, n, nrhs, x,
pdx, "Solution(s)", 0, &fail);
if (fail.code != NE_NOERROR)
{
printf("Error from nag_gen_real_mat_print (x04cac).\n%s\n",
fail.message);
exit_status = 1;
goto END;
}
printf("\nBackward errors (machine-dependent)\n");
for (j = 1; j <= nrhs; ++j)
printf("%11.1e%s", berr[j-1], j%7 == 0?"\n":" ");
printf("\nEstimated forward error bounds (machine-dependent)\n");
for (j = 1; j <= nrhs; ++j)
printf("%11.1e%s", ferr[j-1], j%7 == 0?"\n":" ");
printf("\n");
END:
NAG_FREE(afp);
NAG_FREE(ap);
NAG_FREE(b);
NAG_FREE(berr);
NAG_FREE(ferr);
NAG_FREE(x);
return exit_status;
}
```