/* nag_blast_dtrsv (f16pjc) Example Program.
*
* Copyright 2022 Numerical Algorithms Group.
*
* Mark 28.4, 2022.
*/
#include <nag.h>
#include <stdio.h>
int main(void) {
/* Scalars */
double alpha;
Integer exit_status, i, incx, j, n, pda, xlen;
/* Arrays */
double *a = 0, *x = 0;
char nag_enum_arg[40];
/* Nag Types */
NagError fail;
Nag_OrderType order;
Nag_TransType trans;
Nag_UploType uplo;
Nag_DiagType diag;
#ifdef NAG_COLUMN_MAJOR
#define A(I, J) a[(J - 1) * pda + I - 1]
order = Nag_ColMajor;
#else
#define A(I, J) a[(I - 1) * pda + J - 1]
order = Nag_RowMajor;
#endif
exit_status = 0;
INIT_FAIL(fail);
printf("nag_blast_dtrsv (f16pjc) Example Program Results\n\n");
/* Skip heading in data file */
scanf("%*[^\n] ");
/* Read the problem dimensions */
scanf("%" NAG_IFMT "%*[^\n] ", &n);
/* Read the uplo storage 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);
/* Read the unit-diagonal parameter */
scanf("%39s%*[^\n] ", nag_enum_arg);
/* nag_enum_name_to_value (x04nac), see above. */
diag = (Nag_DiagType)nag_enum_name_to_value(nag_enum_arg);
/* Read scalar parameters */
scanf("%lf%*[^\n] ", &alpha);
/* Read increment parameter */
scanf("%" NAG_IFMT "%*[^\n] ", &incx);
pda = n;
xlen = MAX(1, 1 + (n - 1) * ABS(incx));
if (n > 0) {
/* Allocate memory */
if (!(a = NAG_ALLOC(pda * n, double)) || !(x = NAG_ALLOC(xlen, double))) {
printf("Allocation failure\n");
exit_status = -1;
goto END;
}
} else {
printf("Invalid n\n");
exit_status = 1;
return exit_status;
}
/* Input matrix A and vector x */
if (uplo == Nag_Upper) {
for (i = 1; i <= n; ++i) {
if (diag == Nag_NonUnitDiag)
scanf("%lf", &A(i, i));
for (j = i + 1; j <= n; ++j)
scanf("%lf", &A(i, j));
}
scanf("%*[^\n] ");
} else {
for (i = 1; i <= n; ++i) {
for (j = 1; j < i; ++j)
scanf("%lf", &A(i, j));
if (diag == Nag_NonUnitDiag)
scanf("%lf", &A(i, i));
}
scanf("%*[^\n] ");
}
for (i = 0; i < xlen; ++i)
scanf("%lf%*[^\n] ", &x[i]);
/* nag_blast_dtrsv (f16pjc).
* Solution of real triangular system of linear equations.
*
*/
nag_blast_dtrsv(order, uplo, trans, diag, n, alpha, a, pda, x, incx, &fail);
if (fail.code != NE_NOERROR) {
printf("Error from nag_blast_dtrsv (f16pjc).\n%s\n", fail.message);
exit_status = 1;
goto END;
}
/* Print output vector x */
printf("%s\n", " Solution x:");
for (i = 0; i < xlen; ++i) {
printf("%11f\n", x[i]);
}
END:
NAG_FREE(a);
NAG_FREE(x);
return exit_status;
}