```/* nag_dsyr2k (f16yrc) Example Program.
*
* Copyright 2017 Numerical Algorithms Group.
*
* Mark 26.2, 2017.
*/

#include <stdio.h>
#include <nag.h>
#include <nag_stdlib.h>
#include <nagf16.h>
#include <nagx04.h>

int main(void)
{

/* Scalars */
double alpha, beta;

/* Arrays */
double *a = 0, *b = 0, *c = 0;
char nag_enum_arg[40];

/* Nag Types */
NagError fail;
Nag_OrderType order;
Nag_UploType uplo;
Nag_TransType trans;
Nag_MatrixType matrix;

#ifdef NAG_COLUMN_MAJOR
#define A(I, J) a[(J-1)*pda + I - 1]
#define B(I, J) b[(J-1)*pdb + I - 1]
#define C(I, J) c[(J-1)*pdc + I - 1]
order = Nag_ColMajor;
#else
#define A(I, J) a[(I-1)*pda + J - 1]
#define B(I, J) b[(I-1)*pdb + J - 1]
#define C(I, J) c[(I-1)*pdc + J - 1]
order = Nag_RowMajor;
#endif

exit_status = 0;
INIT_FAIL(fail);

printf("nag_dsyr2k (f16yrc) Example Program Results\n\n");

/* Skip heading in data file */
scanf("%*[^\n] ");

/* Read the problem dimensions */
scanf("%" NAG_IFMT "%" NAG_IFMT "%*[^\n] ", &n, &k);

/* Read the uplo parameter */
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);
/* Read the transpose parameter */
scanf("%39s%*[^\n] ", nag_enum_arg);
/* nag_enum_name_to_value (x04nac), see above. */
trans = (Nag_TransType) nag_enum_name_to_value(nag_enum_arg);
scanf("%lf%lf%*[^\n] ", &alpha, &beta);

if (trans == Nag_NoTrans) {
}
else {
}

#ifdef NAG_COLUMN_MAJOR
#else
#endif
pdb = pda;
pdc = n;
if (k > 0 && n > 0) {
/* Allocate memory */
if (!(a = NAG_ALLOC(k * n, double)) ||
!(b = NAG_ALLOC(k * n, double)) || !(c = NAG_ALLOC(n * n, double)))
{
printf("Allocation failure\n");
exit_status = -1;
goto END;
}
}
else {
printf("Invalid k or n\n");
exit_status = 1;
goto END;
}

/* Input matrix A. */
for (i = 1; i <= adim1; ++i) {
for (j = 1; j <= adim2; ++j)
scanf("%lf", &A(i, j));
scanf("%*[^\n] ");
}
/* Input matrix B. */
for (i = 1; i <= adim1; ++i) {
for (j = 1; j <= adim2; ++j)
scanf("%lf", &B(i, j));
scanf("%*[^\n] ");
}
/* Input matrix C. */
if (uplo == Nag_Upper) {
for (i = 1; i <= n; ++i) {
for (j = i; j <= n; ++j)
scanf("%lf", &C(i, j));
}
scanf("%*[^\n] ");
}
else {
for (i = 1; i <= n; ++i) {
for (j = 1; j <= i; ++j)
scanf("%lf", &C(i, j));
}
scanf("%*[^\n] ");
}

/* nag_dsyr2k (f16yrc).
* Rank 2k update of symmetric matrix.
*
*/
nag_dsyr2k(order, uplo, trans, n, k, alpha, a, pda, b, pdb, beta,
c, pdc, &fail);
if (fail.code != NE_NOERROR) {
printf("Error from nag_dsyr2k.\n%s\n", fail.message);
exit_status = 1;
goto END;
}
if (uplo == Nag_Upper) {
matrix = Nag_UpperMatrix;
}
else {
matrix = Nag_LowerMatrix;
}
/* Print updated matrix C */
/* nag_gen_real_mat_print (x04cac).
* Print real general matrix (easy-to-use)
*/
fflush(stdout);
nag_gen_real_mat_print(order, matrix, Nag_NonUnitDiag, n,
n, c, pdc, "Updated Matrix C", 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;
}
END:
NAG_FREE(a);
NAG_FREE(b);
NAG_FREE(c);

return exit_status;
}
```