```/* nag_matop_dtpttf (f01vjc) Example Program.
*
* Copyright 2019 Numerical Algorithms Group.
*
* Mark 27.0, 2019.
*/

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

int main(void)
{
/* Scalars */
Integer exit_status = 0, indent = 0, ncols = 80;
Integer i, j, k, lar1, lar2, lenap, lenar, n, pdar, q;
/* Arrays */
double *ap = 0, *ar = 0;
char nag_enum_transr[40], nag_enum_uplo[40], form[] = "%5.2f";
/* Nag Types */
Nag_OrderType order;
Nag_RFP_Store transr;
Nag_UploType uplo;
NagError fail;

#ifdef NAG_COLUMN_MAJOR
order = Nag_ColMajor;
#define KU(I,J) (I + J*(J+1)/2)
#define KL(I,J) (J*(n-1) - J*(J-1)/2 + I)
#else
order = Nag_RowMajor;
#define KL(I,J) (J + I*(I+1)/2)
#define KU(I,J) (I*(n-1) - I*(I-1)/2 + J)
#endif

INIT_FAIL(fail);

printf("nag_matop_dtpttf (f01vjc) Example Program Results\n\n");
/* Skip heading in data file */
scanf("%*[^\n] ");
scanf("%" NAG_IFMT "%*[^\n] ", &n);
scanf("%39s ", nag_enum_transr);
scanf("%39s  %*[^\n] ", nag_enum_uplo);
lenap = (n * (n + 1)) / 2;
lenar = lenap;
if (!(ap = NAG_ALLOC(lenap, double)) || !(ar = NAG_ALLOC(lenar, double)))
{
printf("Allocation failure\n");
exit_status = -1;
goto END;
}
transr = (Nag_RFP_Store) nag_enum_name_to_value(nag_enum_transr);
uplo = (Nag_UploType) nag_enum_name_to_value(nag_enum_uplo);

/* Read and print the packed vector ap using macros KL or KU. */
printf(" Packed Array ap (printed using KL/KU macros):\n\n");
for (i = 0; i < n; i++) {
if (uplo == Nag_Upper) {
for (j = i; j < n; j++)
scanf("%lf ", &ap[KU(i, j)]);
for (j = 0; j < i; j++)
printf("%6s", " ");
for (j = i; j < n; j++)
printf("%6.2f", ap[KU(i, j)]);
}
else {
for (j = 0; j <= i; j++)
scanf("%lf ", &ap[KL(i, j)]);
for (j = 0; j <= i; j++)
printf("%6.2f", ap[KL(i, j)]);
}
printf("\n");
}
printf("\n");

/* Convert real triangular matrix from packed to Rectangular Full Packed
* form using nag_matop_dtpttf (f01vjc).
*/
nag_matop_dtpttf(order, transr, uplo, n, ap, ar, &fail);
if (fail.code != NE_NOERROR) {
printf("Error from nag_matop_dtpttf (f01vjc).\n%s\n", fail.message);
exit_status = 1;
goto END;
}

/* Print the Rectangular Full Packed array
* showing how the elements are arranged.
*/
k = n / 2;
q = n - k;
if (transr == Nag_RFP_Normal) {
lar1 = 2 * k + 1;
lar2 = q;
}
else {
lar1 = q;
lar2 = 2 * k + 1;
}
if (order == Nag_RowMajor) {
pdar = lar2;
}
else {
pdar = lar1;
}
/* nag_file_print_matrix_real_gen_comp (x04cbc).
* Print real general matrix (comprehensive).
*/
fflush(stdout);
nag_file_print_matrix_real_gen_comp(order, Nag_GeneralMatrix, Nag_NonUnitDiag, lar1,
lar2, ar, pdar, form,
"RFP Packed Array AR "
"(structural representation):",
Nag_IntegerLabels, NULL, Nag_IntegerLabels,
NULL, ncols, indent, NULL, &fail);
if (fail.code != NE_NOERROR) {
printf("Error from nag_file_print_matrix_real_gen_comp (x04cbc).\n%s\n",
fail.message);
exit_status = 1;
}

END:
NAG_FREE(ap);
NAG_FREE(ar);
return exit_status;
}
```