/* nag_matop_real_gen_matrix_actexp (f01gac) Example Program.
*
* Copyright 2024 Numerical Algorithms Group.
*
* Mark 30.1, 2024.
*/
#include <math.h>
#include <nag.h>
int main(void) {
/* Scalars */
Integer exit_status = 0;
Integer i, j, m, n, lda, ldb;
double t;
/* Arrays */
double *a = 0;
double *b = 0;
/* Nag Types */
Nag_OrderType order;
NagError fail;
INIT_FAIL(fail);
#define A(I, J) a[(J - 1) * lda + I - 1]
#define B(I, J) b[(J - 1) * ldb + I - 1]
order = Nag_ColMajor;
/* Output preamble */
printf("nag_matop_real_gen_matrix_actexp (f01gac) ");
printf("Example Program Results\n\n");
fflush(stdout);
/* Skip heading in data file */
scanf("%*[^\n]");
/* Read in the problem size and the value of the parameter t */
scanf("%" NAG_IFMT " %" NAG_IFMT " %lf%*[^\n]", &n, &m, &t);
lda = n;
ldb = n;
if (!(a = NAG_ALLOC(n * n, double)) || !(b = NAG_ALLOC(n * m, double))) {
printf("Allocation failure\n");
exit_status = -1;
goto END;
}
/* Read in the matrix a from data file */
for (i = 1; i <= n; i++)
for (j = 1; j <= n; j++)
scanf("%lf", &A(i, j));
scanf("%*[^\n]");
/* Read in the matrix b from data file */
for (i = 1; i <= n; i++)
for (j = 1; j <= m; j++)
scanf("%lf", &B(i, j));
scanf("%*[^\n]");
/* Find exp(tA) B using
* nag_matop_real_gen_matrix_actexp (f01gac)
* Action of the exponential of a real matrix on a real matrix
*/
nag_matop_real_gen_matrix_actexp(n, m, a, lda, b, ldb, t, &fail);
if (fail.code != NE_NOERROR) {
printf("Error from nag_matop_real_gen_matrix_actexp (f01gac)\n%s\n",
fail.message);
exit_status = 1;
goto END;
}
/* Print solution using
* nag_file_print_matrix_real_gen (x04cac)
* Print real general matrix (easy-to-use)
*/
nag_file_print_matrix_real_gen(order, Nag_GeneralMatrix, Nag_NonUnitDiag, n,
m, b, ldb, "exp(tA) B", NULL, &fail);
if (fail.code != NE_NOERROR) {
printf("Error from nag_file_print_matrix_real_gen (x04cac)\n%s\n",
fail.message);
exit_status = 2;
goto END;
}
END:
NAG_FREE(a);
NAG_FREE(b);
return exit_status;
}