```/* nag_dtfttp (f01vlc) Example Program.
*
* Copyright 2014 Numerical Algorithms Group.
*
* Mark 25, 2014.
*/

#include <stdio.h>
#include <nag.h>
#include <nag_stdlib.h>
#include <nagf01.h>
#include <nagx04.h>

int main(void)
{
/* Scalars */
Integer       exit_status = 0, inc1 = 1, indent = 0, ncols = 80;
Integer       i, j, k, lar1, lar2, lenap, lenar, mx, n, nx, 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 AR(I,J) ar[J*pdar + I]
#define KU(I,J,N) (I + J*(J+1)/2)
#define KL(I,J,N) (J*(N-1) - J*(J-1)/2 + I)
#else
order = Nag_RowMajor;
#define AR(I,J) ar[I*pdar + J]
#define KL(I,J,N) (J + I*(I+1)/2)
#define KU(I,J,N) (I*(N-1) - I*(I-1)/2 + J)
#endif

INIT_FAIL(fail);

printf("nag_dtfttp (f01vlc) 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;
}
/* Nag_RFP_Store */
transr = (Nag_RFP_Store) nag_enum_name_to_value(nag_enum_transr);
uplo = (Nag_UploType) nag_enum_name_to_value(nag_enum_uplo);

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;
}
/* Read an RFP matrix into array AR. */
for (i = 0; i < lar1; i++) {
for (j = 0; j < lar2; j++) scanf("%lf ", &AR(i,j));
}

/* Print the packed Rectangular Full Packed array */
if (order==Nag_RowMajor) {
mx = inc1;
nx = lenar;
} else {
mx = lenar;
nx = inc1;
}
fflush(stdout);
nag_gen_real_mat_print_comp(order, Nag_GeneralMatrix, Nag_NonUnitDiag, mx, nx,
ar, lenar, form, "RFP Packed Array AR:",
Nag_IntegerLabels, NULL, Nag_NoLabels, NULL,
ncols, indent, NULL, &fail);
if (fail.code != NE_NOERROR) {
printf("Error from nag_gen_complx_mat_print_comp (x04dbc).\n%s\n",
fail.message);
exit_status = 1;
}
printf("\n");

/* Convert real triangular matrix from Rectangular Full Packed to
* packed vector form using nag_dtfttp (f01vlc).
*/
nag_dtfttp(order, transr, uplo, n, ar, ap, &fail);
if (fail.code != NE_NOERROR) {
printf("Error from nag_dtfttp (f01vlc).\n%s\n",
fail.message);
exit_status = 1;
goto END;
}

/* Print the packed vector */
if (order==Nag_RowMajor) {
mx = inc1;
nx = lenap;
} else {
mx = lenap;
nx = inc1;
}
fflush(stdout);
nag_gen_real_mat_print_comp(order, Nag_GeneralMatrix, Nag_NonUnitDiag, mx, nx,
ap, lenap, form, "Packed Array AP:",
Nag_IntegerLabels, NULL, Nag_NoLabels, NULL,
ncols, indent, NULL, &fail);
if (fail.code != NE_NOERROR) {
printf("Error from nag_gen_real_mat_print_comp (x04cbc).\n%s\n",
fail.message);
exit_status = 1;
}
printf("\n");

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

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