NAG Library Manual, Mark 29.3
```/* nag_wav_dim3_sngl_fwd (c09fac) Example Program.
*
* Copyright 2023 Numerical Algorithms Group.
*
* Mark 29.3, 2023.
*/
#include <math.h>
#include <nag.h>
#include <stdio.h>

#define A(I, J, K) a[I - 1 + (J - 1) * lda + (K - 1) * lda * sda]
#define B(I, J, K) b[I - 1 + (J - 1) * ldb + (K - 1) * ldb * sdb]
#define D(I, J, K) d[I - 1 + (J - 1) * nwcm + (K - 1) * nwcm * nwcn]

int main(void) {
/* Scalars */
Integer exit_status = 0, zero = 0;
Integer cindex, i, j, k, lda, ldb, lenc;
Integer m, n, fr, nf, nwcfr, nwcm, nwcn, nwct, nwl, sda, sdb;
/* Arrays */
char mode[25], wavnam[25];
double *a = 0, *b = 0, *c = 0, *d = 0;
Integer icomm[260];
/* Nag Types */
Nag_WaveletMode modenum;
Nag_MatrixType matrix = Nag_GeneralMatrix;
Nag_OrderType order = Nag_ColMajor;
Nag_DiagType diag = Nag_NonUnitDiag;
NagError fail;

INIT_FAIL(fail);

printf("nag_wav_dim3_sngl_fwd (c09fac) Example Program Results\n\n");
fflush(stdout);

scanf("%*[^\n] %" NAG_IFMT "%" NAG_IFMT "%" NAG_IFMT "%*[^\n]", &m, &n, &fr);
lda = m;
ldb = m;
sda = n;
sdb = n;
scanf("%24s%24s%*[^\n]\n", wavnam, mode);

if (!(a = NAG_ALLOC((lda) * (sda) * (fr), double)) ||
!(b = NAG_ALLOC((ldb) * (sdb) * (fr), double))) {
printf("Allocation failure\n");
exit_status = 1;
goto END;
}

printf("Parameters read from file :: \n");
printf("DWT :: Wavelet  : %s\n", wavnam);
printf("       End mode : %s\n", mode);
printf("       m  : %4" NAG_IFMT "\n", m);
printf("       n  : %4" NAG_IFMT "\n", n);
printf("       fr : %4" NAG_IFMT "\n\n", fr);

/* nag_enum_name_to_value (x04nac).
* Converts NAG enum member name to value
*/
modenum = (Nag_WaveletMode)nag_enum_name_to_value(mode);

for (k = 1; k <= fr; k++) {
for (i = 1; i <= m; i++) {
for (j = 1; j <= n; j++)
scanf("%lf", &A(i, j, k));
}
scanf("%*[^\n] ");
}

/* Print out the input data */
printf("Input Data :\n");
fflush(stdout);
for (k = 1; k <= fr; k++) {
/* nag_file_print_matrix_real_gen_comp (x04cbc).
* Prints out a matrix.
*/
nag_file_print_matrix_real_gen_comp(order, matrix, diag, m, n, &A(1, 1, k),
lda, "%8.4f", " ", Nag_NoLabels, 0,
Nag_NoLabels, 0, 80, 0, 0, &fail);
if (fail.code != NE_NOERROR) {
printf("Error from nag_file_print_matrix_real_gen_comp (x04cbc).\n%s\n",
fail.message);
exit_status = 2;
goto END;
}
printf("\n");
fflush(stdout);
}

/* nag_wav_dim3_init (c09acc).
* Three-dimensional wavelet filter initialization
*/
nag_wav_dim3_init(wavnamenum, Nag_SingleLevel, modenum, m, n, fr, &nwl, &nf,
&nwct, &nwcn, &nwcfr, icomm, &fail);
if (fail.code != NE_NOERROR) {
printf("Error from nag_wav_dim3_init (c09acc).\n%s\n", fail.message);
exit_status = 3;
goto END;
}

/* Calculate the number of wavelet coefficients in
* the first dimension, nwcm.
*/
nwcm = nwct / (8 * nwcn * nwcfr);
lenc = nwct;

/* Allocate space for the coefficients array, C */
if (!(c = NAG_ALLOC((lenc), double))) {
printf("Allocation failure\n");
exit_status = 4;
goto END;
}

/* nag_wav_dim3_sngl_fwd (c09fac).
* Three-dimensional discrete wavelet transform
*/
nag_wav_dim3_sngl_fwd(m, n, fr, a, lda, sda, lenc, c, icomm, &fail);
if (fail.code != NE_NOERROR) {
printf("Error from nag_wav_dim3_sngl_fwd (c09fac).\n%s\n", fail.message);
exit_status = 5;
goto END;
}

/* Allocate space for extraction of coefficients of a single type */
if (!(d = NAG_ALLOC((nwcm) * (nwcn) * (nwcfr), double))) {
printf("Allocation failure\n");
exit_status = 6;
goto END;
}

for (cindex = 0; cindex <= 7; cindex++) {
/* Use the extraction routine c09fyc to retrieve the required
* coefficients.
*/

/* nag_wav_dim3_coeff_ext (c09fyc).
* Extract the nominated coefficients.
*/
nag_wav_dim3_coeff_ext(zero, cindex, lenc, c, d, nwcm, nwcn, icomm, &fail);
if (fail.code != NE_NOERROR) {
printf("Error from nag_wav_dim3_coeff_ext (c09fyc).\n%s\n", fail.message);
exit_status = 7;
goto END;
}

/* Print out the extracted coefficients */
switch (cindex) {
case 0:
printf("Approximation coefficients (LLL)\n");
break;
case 1:
printf("Detail coefficients (LLH)\n");
break;
case 2:
printf("Detail coefficients (LHL)\n");
break;
case 3:
printf("Detail coefficients (LHH)\n");
break;
case 4:
printf("Detail coefficients (HLL)\n");
break;
case 5:
printf("Detail coefficients (HLH)\n");
break;
case 6:
printf("Detail coefficients (HHL)\n");
break;
case 7:
printf("Detail coefficients (HHH)\n");
break;
}

for (i = 1; i <= nwcm; i++) {
if (i == 1) {
printf("Coefficients   ");
for (k = 1; k <= nwcfr; k++) {
printf("Frame %4" NAG_IFMT, k);
for (j = 1; j <= 9 * nwcn - 8; j++)
printf(" ");
}
printf("\n");
}

for (k = 1; k <= nwcfr; k++) {
if (k == 1 && i == 1)
printf("%5" NAG_IFMT "%8s", cindex, " ");
else if (k == 1)
printf("%13s", " ");
else
printf("%2s", " ");
for (j = 1; j <= nwcn; j++) {
printf("%8.4f ", D(i, j, k));
}
}
printf("\n");
}
printf("\n");
}
fflush(stdout);

/* nag_wav_dim3_sngl_inv (c09fbc).
* Three-dimensional inverse discrete wavelet transform
*/
nag_wav_dim3_sngl_inv(m, n, fr, lenc, c, b, ldb, sdb, icomm, &fail);
if (fail.code != NE_NOERROR) {
printf("Error from nag_wav_dim3_sngl_inv (c09fbc).\n%s\n", fail.message);
exit_status = 8;
goto END;
}

printf("Output Data :\n");
fflush(stdout);
for (k = 1; k <= fr; k++) {
/* nag_file_print_matrix_real_gen_comp (x04cbc).
* Prints out a matrix.
*/
nag_file_print_matrix_real_gen_comp(order, matrix, diag, m, n, &B(1, 1, k),
ldb, "%8.4f", " ", Nag_NoLabels, 0,
Nag_NoLabels, 0, 80, 0, 0, &fail);
if (fail.code != NE_NOERROR) {
printf("Error from nag_file_print_matrix_real_gen_comp (x04cbc).\n%s\n",
fail.message);
exit_status = 9;
goto END;
}
printf("\n");
fflush(stdout);
}

END:
NAG_FREE(a);
NAG_FREE(b);
NAG_FREE(c);
NAG_FREE(d);

return exit_status;
}
```