/* nag_zptcon (f07juc) Example Program. * * Copyright 2004 Numerical Algorithms Group. * * Mark 23, 2011. * * UNFINISHED - replace commented out climp calls */ #include #include #include #include #include int main(void) { #define CABS(e) sqrt(e.re * e.re + e.im * e.im) /* Scalars */ double anorm, rcond; Integer exit_status = 0, i, n; /* Arrays */ Complex *e = 0; double *d = 0; /* Nag Types */ NagError fail; INIT_FAIL(fail); printf("nag_zptcon (f07juc) Example Program Results\n\n"); /* Skip heading in data file */ scanf("%*[^\n]"); scanf("%ld%*[^\n]", &n); if (n < 0) { printf("Invalid n\n"); exit_status = 1; goto END; } /* Allocate memory */ if (!(e = NAG_ALLOC(n-1, Complex)) || !(d = NAG_ALLOC(n, double))) { printf("Allocation failure\n"); exit_status = -1; goto END; } /* Read the lower bidiagonal part of the tridiagonal matrix A from */ /* data file */ for (i = 0; i < n; ++i) scanf("%lf", &d[i]); scanf("%*[^\n]"); for (i = 0; i < n - 1; ++i) scanf(" ( %lf , %lf )", &e[i].re, &e[i].im); scanf("%*[^\n]"); /* Compute the 1-norm of A */ anorm = MAX(ABS(d[0])+CABS(e[0]), CABS(e[n-2])+ABS(d[n-1])); for (i = 1; i < n-1; ++i) anorm = MAX(anorm, ABS(d[i])+CABS(e[i])+CABS(e[i-1])); /* Factorize A using nag_zpttrf (f07jrc). */ nag_zpttrf(n, d, e, &fail); if (fail.code != NE_NOERROR) { printf("Error from nag_zpttrf (f07jrc).\n%s\n", fail.message); exit_status = 1; goto END; } /* Estimate the condition number of A using nag_zptcon (f07juc). */ nag_zptcon(n, d, e, anorm, &rcond, &fail); if (fail.code != NE_NOERROR) { printf("Error from nag_zptcon (f07juc).\n%s\n", fail.message); exit_status = 1; goto END; } /* Print the estimated condition number */ 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. RCOND = %11.2e\n\n", rcond); END: NAG_FREE(e); NAG_FREE(d); return exit_status; }