/* nag_zero_nonlin_eqns_rcomm (c05qdc) Example Program. * * Copyright 2013 Numerical Algorithms Group. * * Mark 24, 2013. */ #include #include #include #include #include #include #include #ifdef __cplusplus extern "C" { #endif static void NAG_CALL fcn(Integer n, const double x[], double fvec[]); #ifdef __cplusplus } #endif int main(void) { Integer exit_status = 0, i, n = 9, irevcm, ml, mu; double *diag = 0, *fjac = 0, *fvec = 0, *qtf = 0, *r = 0, *x = 0, *rwsav = 0; Integer *iwsav = 0; double epsfcn, factor, xtol; /* Nag Types */ NagError fail; Nag_ScaleType scale_mode; INIT_FAIL(fail); printf("nag_zero_nonlin_eqns_rcomm (c05qdc) Example Program Results\n"); if (n > 0) { if (!(diag = NAG_ALLOC(n, double)) || !(fjac = NAG_ALLOC(n*n, double)) || !(fvec = NAG_ALLOC(n, double)) || !(qtf = NAG_ALLOC(n, double)) || !(r = NAG_ALLOC(n*(n+1)/2, double)) || !(x = NAG_ALLOC(n, double)) || !(iwsav = NAG_ALLOC(17, Integer)) || !(rwsav = NAG_ALLOC(4*n + 10, double))) { printf("Allocation failure\n"); exit_status = -1; goto END; } } else { printf("Invalid n.\n"); exit_status = 1; goto END; } /* The following starting values provide a rough solution. */ for (i = 0; i < n; i++) x[i] = -1.0; /* nag_machine_precision (x02ajc). * The machine precision */ xtol = sqrt(nag_machine_precision); for (i = 0; i < n; i++) diag[i] = 1.0; ml = 1; mu = 1; epsfcn = 0.0; scale_mode = Nag_ScaleProvided; factor = 100.0; irevcm = 0; /* nag_zero_nonlin_eqns_rcomm (c05qdc). * Solution of a system of nonlinear equations (function values only, * reverse communication) */ do { nag_zero_nonlin_eqns_rcomm(&irevcm, n, x, fvec, xtol, ml, mu, epsfcn, scale_mode, diag, factor, fjac, r, qtf, iwsav, rwsav, &fail); switch (irevcm) { case 1: /* x and fvec are available for printing */ break; case 2: fcn(n, x, fvec); break; } } while (irevcm != 0); if (fail.code != NE_NOERROR) { printf("Error from nag_zero_nonlin_eqns_rcomm (c05qdc).\n%s\n", fail.message); exit_status = 1; if (fail.code != NE_TOO_SMALL && fail.code != NE_NO_IMPROVEMENT) goto END; } printf(fail.code == NE_NOERROR ? "Final approximate" : "Approximate"); printf(" solution\n\n"); for (i = 0; i < n; i++) printf("%12.4f%s", x[i], (i%3 == 2 || i == n-1)?"\n":" "); if (fail.code != NE_NOERROR) exit_status = 2; END: NAG_FREE(diag); NAG_FREE(fjac); NAG_FREE(fvec); NAG_FREE(qtf); NAG_FREE(r); NAG_FREE(x); NAG_FREE(iwsav); NAG_FREE(rwsav); return exit_status; } static void NAG_CALL fcn(Integer n, const double x[], double fvec[]) { Integer k; for (k = 0; k < n; ++k) { fvec[k] = (3.0-x[k]*2.0)*x[k]+1.0; if (k > 0) fvec[k] -= x[k-1]; if (k < n-1) fvec[k] -= x[k+1]*2.0; } }