/* nag_real_lu (f03afc) Example Program. * * Copyright 1990 Numerical Algorithms Group. * * Mark 2 revised, 1992. * Mark 8 revised, 2004. */ #include #include #include #include #include #define A(I, J) a[(I) *tda + J] int main(void) { Integer dete, exit_status = 0, i, j, n, *pivot = 0, tda; NagError fail; double *a = 0, detf, two = 2.0; INIT_FAIL(fail); printf("nag_real_lu (f03afc) Example Program Results\n"); /* Skip heading in data file */ scanf("%*[^\n]"); scanf("%" NAG_IFMT "", &n); if (n >= 1) { if (!(a = NAG_ALLOC(n*n, double)) || !(pivot = NAG_ALLOC(n, Integer))) { printf("Allocation failure\n"); exit_status = -1; goto END; } tda = n; } else { printf("Invalid n.\n"); exit_status = 1; return exit_status; } for (i = 0; i < n; i++) for (j = 0; j < n; j++) scanf("%lf", &A(i, j)); /* nag_real_lu (f03afc). * LU factorization and determinant of real matrix */ nag_real_lu(n, a, tda, pivot, &detf, &dete, &fail); if (fail.code != NE_NOERROR) { printf("Error from nag_real_lu (f03afc).\n%s\n", fail.message); exit_status = 1; goto END; } else { printf("Array A after factorization\n"); for (i = 0; i < n; i++) for (j = 0; j < n; j++) printf("%9.4f%s", A(i, j), (j%8 == 7 || j == n-1)?"\n":" "); printf("\nArray P\n"); for (i = 0; i < n; i++) printf("%3" NAG_IFMT "%s", pivot[i], (i%8 == 7 || i == n-1)?"\n":" "); printf("\ndetf = %9.4f dete = %2" NAG_IFMT "\n", detf, dete); detf = detf * pow(two, (double) dete); printf("\nValue of determinant = %9.4f\n", detf); } END: if (a) NAG_FREE(a); if (pivot) NAG_FREE(pivot); return exit_status; }