/* nag_dsytri (f07mjc) 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_enum; Nag_MatrixType matrix; NagError fail; Nag_OrderType order; /* Arrays */ char uplo[2]; Integer *ipiv=0; 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); Vprintf("nag_dsytri (f07mjc) Example Program Results\n\n"); /* Skip heading in data file */ Vscanf("%*[^\n] "); Vscanf("%ld%*[^\n] ", &n); #ifdef NAG_COLUMN_MAJOR pda = n; #else pda = n; #endif /* Allocate memory */ if ( !(ipiv = NAG_ALLOC(n, Integer)) || !(a = NAG_ALLOC(n * n, double)) ) { Vprintf("Allocation failure\n"); exit_status = -1; goto END; } /* Read A from data file */ Vscanf(" ' %1s '%*[^\n] ", uplo); if (*(unsigned char *)uplo == 'L') { uplo_enum = Nag_Lower; matrix = Nag_LowerMatrix; } else if (*(unsigned char *)uplo == 'U') { uplo_enum = Nag_Upper; matrix = Nag_UpperMatrix; } else { Vprintf("Unrecognised character for Nag_UploType type\n"); exit_status = -1; goto END; } if (uplo_enum == Nag_Upper) { for (i = 1; i <= n; ++i) { for (j = i; j <= n; ++j) Vscanf("%lf", &A(i,j)); } Vscanf("%*[^\n] "); } else { for (i = 1; i <= n; ++i) { for (j = 1; j <= i; ++j) Vscanf("%lf", &A(i,j)); } Vscanf("%*[^\n] "); } /* Factorize A */ /* nag_dsytrf (f07mdc). * Bunch-Kaufman factorization of real symmetric indefinite * matrix */ nag_dsytrf(order, uplo_enum, n, a, pda, ipiv, &fail); if (fail.code != NE_NOERROR) { Vprintf("Error from nag_dsytrf (f07mdc).\n%s\n", fail.message); exit_status = 1; goto END; } /* Compute inverse of A */ /* nag_dsytri (f07mjc). * Inverse of real symmetric indefinite matrix, matrix * already factorized by nag_dsytrf (f07mdc) */ nag_dsytri(order, uplo_enum, n, a, pda, ipiv, &fail); if (fail.code != NE_NOERROR) { Vprintf("Error from nag_dsytri (f07mjc).\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) */ nag_gen_real_mat_print(order, matrix, Nag_NonUnitDiag, n, n, a, pda, "Inverse", 0, &fail); if (fail.code != NE_NOERROR) { Vprintf("Error from nag_gen_real_mat_print (x04cac).\n%s\n", fail.message); exit_status = 1; goto END; } END: if (ipiv) NAG_FREE(ipiv); if (a) NAG_FREE(a); return exit_status; }