/* nag_dspcon (f07pgc) Example Program. * * Copyright 2001 Numerical Algorithms Group. * * Mark 7, 2001. */ #include #include #include #include #include #include int main(void) { /* Scalars */ double anorm, rcond; Integer ap_len, i, j, n; Integer exit_status = 0; NagError fail; Nag_UploType uplo; Nag_OrderType order; /* Arrays */ Integer *ipiv = 0; char nag_enum_arg[40]; double *ap = 0; #ifdef NAG_COLUMN_MAJOR #define A_UPPER(I, J) ap[J*(J-1)/2 + I - 1] #define A_LOWER(I, J) ap[(2*n-J)*(J-1)/2 + I - 1] order = Nag_ColMajor; #else #define A_LOWER(I, J) ap[I*(I-1)/2 + J - 1] #define A_UPPER(I, J) ap[(2*n-I)*(I-1)/2 + J - 1] order = Nag_RowMajor; #endif INIT_FAIL(fail); printf("nag_dspcon (f07pgc) Example Program Results\n\n"); /* Skip heading in data file */ scanf("%*[^\n] "); scanf("%ld%*[^\n] ", &n); ap_len = n * (n + 1)/2; /* Allocate memory */ if (!(ipiv = NAG_ALLOC(n, Integer)) || !(ap = NAG_ALLOC(ap_len, 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) { for (i = 1; i <= n; ++i) { for (j = i; j <= n; ++j) scanf("%lf", &A_UPPER(i, j)); } scanf("%*[^\n] "); } else { for (i = 1; i <= n; ++i) { for (j = 1; j <= i; ++j) scanf("%lf", &A_LOWER(i, j)); } scanf("%*[^\n] "); } /* Compute norm of A */ /* nag_dsp_norm (f16rdc). * 1-norm, infinity-norm, Frobenius norm, largest absolute * element, real symmetric matrix, packed storage */ nag_dsp_norm(order, Nag_OneNorm, uplo, n, ap, &anorm, &fail); if (fail.code != NE_NOERROR) { printf("Error from nag_dsp_norm (f16rdc).\n%s\n", fail.message); exit_status = 1; goto END; } /* Factorize A */ /* nag_dsptrf (f07pdc). * Bunch-Kaufman factorization of real symmetric indefinite * matrix, packed storage */ nag_dsptrf(order, uplo, n, ap, ipiv, &fail); if (fail.code != NE_NOERROR) { printf("Error from nag_dsptrf (f07pdc).\n%s\n", fail.message); exit_status = 1; goto END; } /* Estimate condition number */ /* nag_dspcon (f07pgc). * Estimate condition number of real symmetric indefinite * matrix, matrix already factorized by nag_dsptrf (f07pdc), * packed storage */ nag_dspcon(order, uplo, n, ap, ipiv, anorm, &rcond, &fail); if (fail.code != NE_NOERROR) { printf("Error from nag_dspcon (f07pgc).\n%s\n", fail.message); exit_status = 1; goto END; } /* nag_machine_precision (x02ajc). * The machine precision */ if (rcond >= nag_machine_precision) printf("Estimate of condition number =%11.2e\n\n", 1.0/rcond); else printf("A is singular to working precision\n"); END: if (ipiv) NAG_FREE(ipiv); if (ap) NAG_FREE(ap); return exit_status; }