/* nag_dpotri (f07fjc) Example Program. * * Copyright 2001 Numerical Algorithms Group. * * Mark 7, 2001. */ #include #include #include #include #include int main(void) { /* Scalars */ Integer i, j, n, pda; Integer exit_status = 0; Nag_UploType uplo; Nag_MatrixType matrix; NagError fail; Nag_OrderType order; /* Arrays */ char nag_enum_arg[40]; double *a = 0; #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 INIT_FAIL(fail); printf("nag_dpotri (f07fjc) Example Program Results\n\n"); /* Skip heading in data file */ scanf("%*[^\n] "); scanf("%ld%*[^\n] ", &n); #ifdef NAG_COLUMN_MAJOR pda = n; #else pda = n; #endif /* Allocate memory */ if (!(a = NAG_ALLOC(n * n, double))) { printf("Allocation failure\n"); exit_status = -1; goto END; } /* Read A from data file */ scanf(" %s%*[^\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); if (uplo == Nag_Upper) { matrix = Nag_UpperMatrix; for (i = 1; i <= n; ++i) { for (j = i; j <= n; ++j) scanf("%lf", &A(i, j)); } scanf("%*[^\n] "); } else { matrix = Nag_LowerMatrix; for (i = 1; i <= n; ++i) { for (j = 1; j <= i; ++j) scanf("%lf", &A(i, j)); } scanf("%*[^\n] "); } /* Factorize A */ /* 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("Error from nag_dpotrf (f07fdc).\n%s\n", fail.message); exit_status = 1; goto END; } /* Compute inverse of A */ /* nag_dpotri (f07fjc). * Inverse of real symmetric positive-definite matrix, * matrix already factorized by nag_dpotrf (f07fdc) */ nag_dpotri(order, uplo, n, a, pda, &fail); if (fail.code != NE_NOERROR) { printf("Error from nag_dpotri (f07fjc).\n%s\n", fail.message); exit_status = 1; goto END; } /* Print inverse */ /* 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, a, pda, "Inverse", 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: if (a) NAG_FREE(a); return exit_status; }