/* nag_det_real_sym (f03bfc) Example Program. * * Copyright 2011, Numerical Algorithms Group. * * Mark 23, 2011. */ #include #include #include #include #include #include int main(void) { /* Scalars */ Integer exit_status = 0; Integer i, id, j, n, pda; double d; /* Arrays */ char nag_enum_arg[40]; double *a = 0; /* NAG types */ NagError fail; Nag_UploType uplo; Nag_OrderType order; Nag_MatrixType matrix; Nag_DiagType diag = Nag_NonUnitDiag; printf("nag_det_real_sym (f03bfc) Example Program Results\n\n"); /* Skip heading in data file */ scanf("%*[^\n] "); scanf("%ld%*[^\n]", &n); pda = n; if (!(a = NAG_ALLOC(n*n, double))) { printf("Allocation failure\n"); exit_status = -1; goto END; } /* Define matrix element A_ij in terms of elements of array a[k] */ #ifdef NAG_COLUMN_MAJOR order = Nag_ColMajor; #define A(I, J) a[(J-1)*pda+(I-1)] #else order = Nag_RowMajor; #define A(J, I) a[(J-1)*pda+(I-1)] #endif for (i = 1; i <= n; i++) for (j = 1; j <= n; j++) scanf("%lf", &A(i,j)); scanf("%*[^\n] "); scanf("%s %*[^\n] ", nag_enum_arg); /* Nag_Lower */ uplo = (Nag_UploType) nag_enum_name_to_value(nag_enum_arg); if (uplo==Nag_Lower) { matrix = Nag_LowerMatrix; } else { matrix = Nag_UpperMatrix; } INIT_FAIL(fail); /* nag_dpotrf (f07fdc) * Cholesky factorization of real symmetric positive definite matrix */ nag_dpotrf(order, uplo, n, a, pda, &fail); if (fail.code != NE_NOERROR) { printf("%s\n", fail.message); exit_status = 1; goto END; } /* nag_gen_real_mat_print (x04cac) * Print real general matrix (easy-to-use) */ fflush(stdout); nag_gen_real_mat_print(order, matrix, diag, n, n, a, pda, "Array A after factorization", NULL, &fail); if (fail.code != NE_NOERROR) { printf("%s\n", fail.message); exit_status = 2; goto END; } /* nag_det_real_sym(f03bfc) * determinant of factorized real symmetric positive definite matrix */ nag_det_real_sym(order, n, a, pda, &d, &id, &fail); if (fail.code != NE_NOERROR) { printf("%s\n", fail.message); exit_status = 3; goto END; } printf("\nd = %12.5f id = %12" NAG_IFMT "\n", d, id); printf("Value of determinant = %12.5e\n", d*pow(2.0, id)); END: if (a) NAG_FREE(a); return exit_status; }