504 lines
15 KiB
C++
504 lines
15 KiB
C++
/**
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* @file vcs_root1d.cpp
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* Code for a one dimensional root finder program.
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*/
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/*
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* Copyright (2006) Sandia Corporation. Under the terms of
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* Contract DE-AC04-94AL85000 with Sandia Corporation, the
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* U.S. Government retains certain rights in this software.
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*/
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#include "cantera/equil/vcs_internal.h"
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#include <cstdio>
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#include <cstdlib>
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#include <cmath>
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namespace VCSnonideal
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{
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#define TOL_CONV 1.0E-5
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/*****************************************************************************/
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/*****************************************************************************/
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/*****************************************************************************/
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#ifdef DEBUG_MODE
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static void print_funcEval(FILE* fp, double xval, double fval, int its)
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{
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fprintf(fp,"\n");
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fprintf(fp,"...............................................................\n");
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fprintf(fp,".................. vcs_root1d Function Evaluation .............\n");
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fprintf(fp,".................. iteration = %5d ........................\n", its);
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fprintf(fp,".................. value = %12.5g ......................\n", xval);
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fprintf(fp,".................. funct = %12.5g ......................\n", fval);
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fprintf(fp,"...............................................................\n");
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fprintf(fp,"\n");
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}
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#endif
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/*****************************************************************************/
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/*****************************************************************************/
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/*****************************************************************************/
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// One Dimensional Root Finder
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/*
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*
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* vcs_root1d:
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*
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*
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*
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* Following is a nontrial example for vcs_root1d() where the buoyancy of a
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* cylinder floating on water is calculated.
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*
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* @verbatim
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* #include <cmath>
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* #include <cstdlib>
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*
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* #include "equil/vcs_internal.h"
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*
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* const double g_cgs = 980.;
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* const double mass_cyl = 0.066;
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* const double diam_cyl = 0.048;
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* const double rad_cyl = diam_cyl / 2.0;
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* const double len_cyl = 5.46;
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* const double vol_cyl = Pi * diam_cyl * diam_cyl / 4 * len_cyl;
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* const double rho_cyl = mass_cyl / vol_cyl;
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* const double rho_gas = 0.0;
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* const double rho_liq = 1.0;
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* const double sigma = 72.88;
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* // Contact angle in radians
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* const double alpha1 = 40.0 / 180. * Pi;
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*
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* using namespace Cantera;
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* using namespace VCSnonideal;
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*
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* double func_vert(double theta1, double h_2, double rho_c) {
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* double f_grav = - Pi * rad_cyl * rad_cyl * rho_c * g_cgs;
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* double tmp = rad_cyl * rad_cyl * g_cgs;
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* double tmp1 = theta1 + sin(theta1) * cos(theta1) - 2.0 * h_2 / rad_cyl * sin(theta1);
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* double f_buoy = tmp * (Pi * rho_gas + (rho_liq - rho_gas) * tmp1);
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* double f_sten = 2 * sigma * sin(theta1 + alpha1 - Pi);
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* double f_net = f_grav + f_buoy + f_sten;
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* return f_net;
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* }
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* double calc_h2_farfield(double theta1) {
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* double rhs = sigma * (1.0 + cos(alpha1 + theta1));
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* rhs *= 2.0;
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* rhs = rhs / (rho_liq - rho_gas) / g_cgs;
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* double sign = -1.0;
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* if (alpha1 + theta1 < Pi) sign = 1.0;
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* double res = sign * sqrt(rhs);
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* double h2 = res + rad_cyl * cos(theta1);
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* return h2;
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* }
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* double funcZero(double xval, double Vtarget, int varID, void *fptrPassthrough, int *err) {
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* double theta = xval;
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* double h2 = calc_h2_farfield(theta);
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* double fv = func_vert(theta, h2, rho_cyl);
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* return fv;
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* }
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*
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* int main () {
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*
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* double thetamax = Pi;
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* double thetamin = 0.0;
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* int maxit = 1000;
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* int iconv;
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* double thetaR = Pi/2.0;
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* int printLvl = 4;
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*
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* iconv = VCSnonideal::vcsUtil_root1d(thetamin, thetamax, maxit, funcZero,
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* (void *) 0, 0.0, 0, &thetaR, printLvl);
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* printf("theta = %g\n", thetaR);
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* double h2Final = calc_h2_farfield(thetaR);
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* printf("h2Final = %g\n", h2Final);
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* return 0;
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* }
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* @endverbatim
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*
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*/
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int vcsUtil_root1d(double xmin, double xmax, size_t itmax,
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VCS_FUNC_PTR func, void* fptrPassthrough,
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double FuncTargVal, int varID,
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double* xbest, int printLvl)
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{
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static int callNum = 0;
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const char* stre = "vcs_root1d ERROR: ";
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const char* strw = "vcs_root1d WARNING: ";
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bool converged = false;
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int err = 0;
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#ifdef DEBUG_MODE
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char fileName[80];
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FILE* fp = 0;
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#endif
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double x1, x2, xnew, f1, f2, fnew, slope;
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size_t its = 0;
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int posStraddle = 0;
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int retn = VCS_SUCCESS;
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bool foundPosF = false;
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bool foundNegF = false;
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bool foundStraddle = false;
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double xPosF = 0.0;
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double xNegF = 0.0;
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double fnorm; /* A valid norm for the making the function value
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* dimensionless */
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double c[9], f[3], xn1, xn2, x0 = 0.0, f0 = 0.0, root, theta, xquad;
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callNum++;
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#ifdef DEBUG_MODE
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if (printLvl >= 3) {
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sprintf(fileName, "rootfd_%d.log", callNum);
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fp = fopen(fileName, "w");
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fprintf(fp, " Iter TP_its xval Func_val | Reasoning\n");
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fprintf(fp, "-----------------------------------------------------"
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"-------------------------------\n");
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}
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#else
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if (printLvl >= 3) {
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plogf("WARNING: vcsUtil_root1d: printlvl >= 3, but debug mode not turned on\n");
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}
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#endif
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if (xmax <= xmin) {
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plogf("%sxmin and xmax are bad: %g %g\n", stre, xmin, xmax);
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return VCS_PUB_BAD;
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}
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x1 = *xbest;
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if (x1 < xmin || x1 > xmax) {
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x1 = (xmin + xmax) / 2.0;
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}
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f1 = func(x1, FuncTargVal, varID, fptrPassthrough, &err);
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#ifdef DEBUG_MODE
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if (printLvl >= 3) {
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print_funcEval(fp, x1, f1, its);
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fprintf(fp, "%-5d %-5d %-15.5E %-15.5E\n", -2, 0, x1, f1);
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}
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#endif
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if (f1 == 0.0) {
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*xbest = x1;
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return VCS_SUCCESS;
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} else if (f1 > 0.0) {
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foundPosF = true;
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xPosF = x1;
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} else {
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foundNegF = true;
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xNegF = x1;
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}
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x2 = x1 * 1.1;
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if (x2 > xmax) {
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x2 = x1 - (xmax - xmin) / 100.;
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}
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f2 = func(x2, FuncTargVal, varID, fptrPassthrough, &err);
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#ifdef DEBUG_MODE
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if (printLvl >= 3) {
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print_funcEval(fp, x2, f2, its);
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fprintf(fp, "%-5d %-5d %-15.5E %-15.5E", -1, 0, x2, f2);
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}
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#endif
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if (FuncTargVal != 0.0) {
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fnorm = fabs(FuncTargVal) + 1.0E-13;
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} else {
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fnorm = 0.5*(fabs(f1) + fabs(f2)) + fabs(FuncTargVal);
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}
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if (f2 == 0.0) {
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return retn;
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} else if (f2 > 0.0) {
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if (!foundPosF) {
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foundPosF = true;
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xPosF = x2;
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}
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} else {
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if (!foundNegF) {
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foundNegF = true;
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xNegF = x2;
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}
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}
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foundStraddle = foundPosF && foundNegF;
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if (foundStraddle) {
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if (xPosF > xNegF) {
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posStraddle = true;
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} else {
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posStraddle = false;
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}
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}
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do {
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/*
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* Find an estimate of the next point to try based on
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* a linear approximation.
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*/
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slope = (f2 - f1) / (x2 - x1);
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if (slope == 0.0) {
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plogf("%s functions evals produced the same result, %g, at %g and %g\n",
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strw, f2, x1, x2);
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xnew = 2*x2 - x1 + 1.0E-3;
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} else {
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xnew = x2 - f2 / slope;
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}
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#ifdef DEBUG_MODE
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if (printLvl >= 3) {
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fprintf(fp, " | xlin = %-9.4g", xnew);
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}
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#endif
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/*
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* Do a quadratic fit -> Note this algorithm seems
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* to work OK. The quadratic approximation doesn't kick in until
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* the end of the run, when it becomes reliable.
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*/
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if (its > 0) {
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c[0] = 1.;
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c[1] = 1.;
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c[2] = 1.;
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c[3] = x0;
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c[4] = x1;
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c[5] = x2;
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c[6] = SQUARE(x0);
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c[7] = SQUARE(x1);
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c[8] = SQUARE(x2);
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f[0] = - f0;
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f[1] = - f1;
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f[2] = - f2;
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retn = vcsUtil_mlequ(c, 3, 3, f, 1);
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if (retn == 1) {
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goto QUAD_BAIL;
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}
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root = f[1]* f[1] - 4.0 * f[0] * f[2];
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if (root >= 0.0) {
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xn1 = (- f[1] + sqrt(root)) / (2.0 * f[2]);
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xn2 = (- f[1] - sqrt(root)) / (2.0 * f[2]);
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if (fabs(xn2 - x2) < fabs(xn1 - x2) && xn2 > 0.0) {
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xquad = xn2;
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} else {
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xquad = xn1;
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}
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theta = fabs(xquad - xnew) / fabs(xnew - x2);
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theta = std::min(1.0, theta);
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xnew = theta * xnew + (1.0 - theta) * xquad;
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#ifdef DEBUG_MODE
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if (printLvl >= 3) {
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if (theta != 1.0) {
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fprintf(fp, " | xquad = %-9.4g", xnew);
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}
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}
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#endif
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} else {
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/*
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* Pick out situations where the convergence may be
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* accelerated.
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*/
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if ((DSIGN(xnew - x2) == DSIGN(x2 - x1)) &&
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(DSIGN(x2 - x1) == DSIGN(x1 - x0))) {
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xnew += xnew - x2;
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#ifdef DEBUG_MODE
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if (printLvl >= 3) {
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fprintf(fp, " | xquada = %-9.4g", xnew);
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}
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#endif
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}
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}
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}
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QUAD_BAIL:
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;
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/*
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*
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* Put heuristic bounds on the step jump
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*/
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if ((xnew > x1 && xnew < x2) || (xnew < x1 && xnew > x2)) {
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/*
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*
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* If we are doing a jump in between two points, make sure
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* the new trial is between 10% and 90% of the distance
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* between the old points.
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*/
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slope = fabs(x2 - x1) / 10.;
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if (fabs(xnew - x1) < slope) {
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xnew = x1 + DSIGN(xnew-x1) * slope;
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#ifdef DEBUG_MODE
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if (printLvl >= 3) {
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fprintf(fp, " | x10%% = %-9.4g", xnew);
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}
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#endif
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}
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if (fabs(xnew - x2) < slope) {
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xnew = x2 + DSIGN(xnew-x2) * slope;
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#ifdef DEBUG_MODE
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if (printLvl >= 3) {
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fprintf(fp, " | x10%% = %-9.4g", xnew);
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}
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#endif
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}
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} else {
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/*
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* If we are venturing into new ground, only allow the step jump
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* to increase by 100% at each iteration
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*/
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slope = 2.0 * fabs(x2 - x1);
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if (fabs(slope) < fabs(xnew - x2)) {
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xnew = x2 + DSIGN(xnew-x2) * slope;
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#ifdef DEBUG_MODE
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if (printLvl >= 3) {
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fprintf(fp, " | xlimitsize = %-9.4g", xnew);
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}
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#endif
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}
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}
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if (xnew > xmax) {
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xnew = x2 + (xmax - x2) / 2.0;
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#ifdef DEBUG_MODE
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if (printLvl >= 3) {
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fprintf(fp, " | xlimitmax = %-9.4g", xnew);
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}
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#endif
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}
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if (xnew < xmin) {
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xnew = x2 + (x2 - xmin) / 2.0;
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#ifdef DEBUG_MODE
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if (printLvl >= 3) {
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fprintf(fp, " | xlimitmin = %-9.4g", xnew);
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}
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#endif
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}
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if (foundStraddle) {
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#ifdef DEBUG_MODE
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slope = xnew;
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#endif
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if (posStraddle) {
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if (f2 > 0.0) {
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if (xnew > x2) {
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xnew = (xNegF + x2)/2;
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}
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if (xnew < xNegF) {
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xnew = (xNegF + x2)/2;
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}
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} else {
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if (xnew < x2) {
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xnew = (xPosF + x2)/2;
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}
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if (xnew > xPosF) {
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xnew = (xPosF + x2)/2;
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}
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}
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} else {
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if (f2 > 0.0) {
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if (xnew < x2) {
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xnew = (xNegF + x2)/2;
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}
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if (xnew > xNegF) {
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xnew = (xNegF + x2)/2;
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}
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} else {
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if (xnew > x2) {
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xnew = (xPosF + x2)/2;
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}
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if (xnew < xPosF) {
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xnew = (xPosF + x2)/2;
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}
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}
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}
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#ifdef DEBUG_MODE
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if (printLvl >= 3) {
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if (slope != xnew) {
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fprintf(fp, " | xstraddle = %-9.4g", xnew);
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}
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}
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#endif
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}
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fnew = func(xnew, FuncTargVal, varID, fptrPassthrough, &err);
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#ifdef DEBUG_MODE
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if (printLvl >= 3) {
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fprintf(fp,"\n");
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print_funcEval(fp, xnew, fnew, its);
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fprintf(fp, "%-5d %-5d %-15.5E %-15.5E", its, 0, xnew, fnew);
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}
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#endif
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if (foundStraddle) {
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if (posStraddle) {
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if (fnew > 0.0) {
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if (xnew < xPosF) {
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xPosF = xnew;
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}
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} else {
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if (xnew > xNegF) {
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xNegF = xnew;
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}
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}
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} else {
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if (fnew > 0.0) {
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if (xnew > xPosF) {
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xPosF = xnew;
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}
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} else {
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if (xnew < xNegF) {
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xNegF = xnew;
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}
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}
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}
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}
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if (! foundStraddle) {
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if (fnew > 0.0) {
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if (!foundPosF) {
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foundPosF = true;
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xPosF = xnew;
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foundStraddle = true;
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posStraddle = (xPosF > xNegF);
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}
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} else {
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if (!foundNegF) {
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foundNegF = true;
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xNegF = xnew;
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foundStraddle = true;
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posStraddle = (xPosF > xNegF);
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}
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}
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}
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x0 = x1;
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f0 = f1;
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x1 = x2;
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f1 = f2;
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x2 = xnew;
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f2 = fnew;
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if (fabs(fnew / fnorm) < 1.0E-5) {
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converged = true;
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}
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its++;
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} while (! converged && its < itmax);
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if (converged) {
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if (printLvl >= 1) {
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plogf("vcs_root1d success: convergence achieved\n");
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}
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#ifdef DEBUG_MODE
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if (printLvl >= 3) {
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fprintf(fp, " | vcs_root1d success in %d its, fnorm = %g\n", its, fnorm);
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}
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#endif
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} else {
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retn = VCS_FAILED_CONVERGENCE;
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if (printLvl >= 1) {
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plogf("vcs_root1d ERROR: maximum iterations exceeded without convergence\n");
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}
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#ifdef DEBUG_MODE
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if (printLvl >= 3) {
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fprintf(fp, "\nvcs_root1d failure in %d its\n", its);
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}
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#endif
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}
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*xbest = x2;
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#ifdef DEBUG_MODE
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if (printLvl >= 3) {
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fclose(fp);
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}
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#endif
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return retn;
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}
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/*****************************************************************************/
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}
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