annotate scripts/optimization/fsolve.m @ 9628:73e6ad869f08

further correct initial TR step strategy
author Jaroslav Hajek <highegg@gmail.com>
date Tue, 08 Sep 2009 14:27:35 +0200
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1 ## Copyright (C) 2008, 2009 VZLU Prague, a.s.
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2 ##
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3 ## This file is part of Octave.
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4 ##
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5 ## Octave is free software; you can redistribute it and/or modify it
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6 ## under the terms of the GNU General Public License as published by
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7 ## the Free Software Foundation; either version 3 of the License, or (at
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8 ## your option) any later version.
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9 ##
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10 ## Octave is distributed in the hope that it will be useful, but
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11 ## WITHOUT ANY WARRANTY; without even the implied warranty of
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12 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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13 ## General Public License for more details.
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14 ##
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15 ## You should have received a copy of the GNU General Public License
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16 ## along with Octave; see the file COPYING. If not, see
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17 ## <http://www.gnu.org/licenses/>.
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18 ##
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19 ## Author: Jaroslav Hajek <highegg@gmail.com>
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20
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21 ## -*- texinfo -*-
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22 ## @deftypefn {Function File} {} fsolve (@var{fcn}, @var{x0}, @var{options})
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23 ## @deftypefnx {Function File} {[@var{x}, @var{fvec}, @var{info}, @var{output}, @var{fjac}]} = fsolve (@var{fcn}, @dots{})
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24 ## Solve a system of nonlinear equations defined by the function @var{fcn}.
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25 ## @var{fcn} should accepts a vector (array) defining the unknown variables,
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26 ## and return a vector of left-hand sides of the equations. Right-hand sides
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27 ## are defined to be zeros.
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28 ## In other words, this function attempts to determine a vector @var{x} such
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29 ## that @code{@var{fcn} (@var{x})} gives (approximately) all zeros.
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30 ## @var{x0} determines a starting guess. The shape of @var{x0} is preserved
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31 ## in all calls to @var{fcn}, but otherwise it is treated as a column vector.
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32 ## @var{options} is a structure specifying additional options.
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33 ## Currently, @code{fsolve} recognizes these options:
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34 ## @code{"FunValCheck"}, @code{"OutputFcn"}, @code{"TolX"},
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35 ## @code{"TolFun"}, @code{"MaxIter"}, @code{"MaxFunEvals"},
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36 ## @code{"Jacobian"}, @code{"Updating"} and @code{"ComplexEqn"}.
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37 ##
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38 ## If @code{"Jacobian"} is @code{"on"}, it specifies that @var{fcn},
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39 ## called with 2 output arguments, also returns the Jacobian matrix
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40 ## of right-hand sides at the requested point. @code{"TolX"} specifies
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41 ## the termination tolerance in the unknown variables, while
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42 ## @code{"TolFun"} is a tolerance for equations. Default is @code{1e-7}
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43 ## for both @code{"TolX"} and @code{"TolFun"}.
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44 ## If @code{"Updating"} is "on", the function will attempt to use Broyden
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45 ## updates to update the Jacobian, in order to reduce the amount of jacobian
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46 ## calculations.
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47 ## If your user function always calculates the Jacobian (regardless of number
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48 ## of output arguments), this option provides no advantage and should be set to
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49 ## false.
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50 ##
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51 ## @code{"ComplexEqn"} is @code{"on"}, @code{fsolve} will attempt to solve
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52 ## complex equations in complex variables, assuming that the equations possess a
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53 ## complex derivative (i.e., are holomorphic). If this is not what you want,
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54 ## should unpack the real and imaginary parts of the system to get a real
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55 ## system.
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56 ##
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57 ## For description of the other options, see @code{optimset}.
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58 ##
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59 ## On return, @var{fval} contains the value of the function @var{fcn}
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60 ## evaluated at @var{x}, and @var{info} may be one of the following values:
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61 ##
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62 ## @table @asis
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63 ## @item 1
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64 ## Converged to a solution point. Relative residual error is less than specified
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65 ## by TolFun.
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66 ## @item 2
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67 ## Last relative step size was less that TolX.
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68 ## @item 3
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69 ## Last relative decrease in residual was less than TolF.
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70 ## @item 0
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71 ## Iteration limit exceeded.
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72 ## @item -3
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73 ## The trust region radius became excessively small.
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74 ## @end table
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75 ##
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76 ## Note: If you only have a single nonlinear equation of one variable, using
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77 ## @code{fzero} is usually a much better idea.
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78 ## @seealso{fzero, optimset}
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79 ##
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80 ## Note about user-supplied jacobians:
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81 ## As an inherent property of the algorithm, jacobian is always requested for a
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82 ## solution vector whose residual vector is already known, and it is the last
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83 ## accepted successful step. Often this will be one of the last two calls, but
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84 ## not always. If the savings by reusing intermediate results from residual
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85 ## calculation in jacobian calculation are significant, the best strategy is to
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86 ## employ OutputFcn: After a vector is evaluated for residuals, if OutputFcn is
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87 ## called with that vector, then the intermediate results should be saved for
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88 ## future jacobian evaluation, and should be kept until a jacobian evaluation
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89 ## is requested or until outputfcn is called with a different vector, in which
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90 ## case they should be dropped in favor of this most recent vector. A short
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91 ## example how this can be achieved follows:
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92 ##
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93 ## @example
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94 ## function [fvec, fjac] = user_func (x, optimvalues, state)
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95 ## persistent sav = [], sav0 = [];
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96 ## if (nargin == 1)
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97 ## ## evaluation call
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98 ## if (nargout == 1)
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99 ## sav0.x = x; # mark saved vector
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100 ## ## calculate fvec, save results to sav0.
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101 ## elseif (nargout == 2)
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102 ## ## calculate fjac using sav.
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103 ## endif
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104 ## else
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105 ## ## outputfcn call.
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106 ## if (all (x == sav0.x))
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107 ## sav = sav0;
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108 ## endif
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109 ## ## maybe output iteration status, etc.
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110 ## endif
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111 ## endfunction
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112 ##
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113 ## ## @dots{}.
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114 ##
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115 ## fsolve (@@user_func, x0, optimset ("OutputFcn", @@user_func, @dots{}))
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116 ## @end example
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117 ###
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118 ## @end deftypefn
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119
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120 ## PKG_ADD: __all_opts__ ("fsolve");
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121
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122 function [x, fvec, info, output, fjac] = fsolve (fcn, x0, options = struct ())
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123
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124 ## Get default options if requested.
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125 if (nargin == 1 && ischar (fcn) && strcmp (fcn, 'defaults'))
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126 x = optimset ("MaxIter", 400, "MaxFunEvals", Inf, \
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127 "Jacobian", "off", "TolX", 1.5e-8, "TolFun", 1.5e-8,
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128 "OutputFcn", [], "Updating", "on", "FunValCheck", "off",
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129 "ComplexEqn", "off", "FinDiffType", "central");
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130 return;
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131 endif
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132
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133 if (nargin < 2 || nargin > 3 || ! ismatrix (x0))
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134 print_usage ();
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135 endif
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136
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137 if (ischar (fcn))
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138 fcn = str2func (fcn, "global");
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139 endif
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140
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141 xsiz = size (x0);
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142 n = numel (x0);
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143
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144 has_jac = strcmpi (optimget (options, "Jacobian", "off"), "on");
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145 cdif = strcmpi (optimget (options, "FinDiffType", "central"), "central");
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146 maxiter = optimget (options, "MaxIter", 400);
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147 maxfev = optimget (options, "MaxFunEvals", Inf);
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148 outfcn = optimget (options, "OutputFcn");
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149 updating = strcmpi (optimget (options, "Updating", "on"), "on");
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150 complexeqn = strcmpi (optimget (options, "ComplexEqn", "off"), "on");
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151
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152 funvalchk = strcmpi (optimget (options, "FunValCheck", "off"), "on");
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153
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154 if (funvalchk)
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155 ## Replace fcn with a guarded version.
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156 fcn = @(x) guarded_eval (fcn, x, complexeqn);
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157 endif
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158
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159 ## These defaults are rather stringent. I think that normally, user
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160 ## prefers accuracy to performance.
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161
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162 macheps = eps (class (x0));
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163
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164 tolx = optimget (options, "TolX", sqrt (macheps));
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165 tolf = optimget (options, "TolFun", sqrt (macheps));
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166
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167 factor = 1;
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168
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169 niter = 1;
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170 nfev = 1;
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171
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172 x = x0(:);
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173 info = 0;
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174
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175 ## Initial evaluation.
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176 ## Handle arbitrary shapes of x and f and remember them.
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177 fvec = fcn (reshape (x, xsiz));
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178 fsiz = size (fvec);
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179 fvec = fvec(:);
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180 fn = norm (fvec);
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181 m = length (fvec);
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182 n = length (x);
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183
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184 if (! isempty (outfcn))
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185 optimvalues.iter = niter;
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186 optimvalues.funccount = nfev;
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187 optimvalues.fval = fn;
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188 optimvalues.searchdirection = zeros (n, 1);
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189 state = 'init';
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190 stop = outfcn (x, optimvalues, state);
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191 if (stop)
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192 info = -1;
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193 break;
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194 endif
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195 endif
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196
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197 nsuciter = 0;
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198
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199 ## Outer loop.
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200 while (niter < maxiter && nfev < maxfev && ! info)
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201
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202 ## Calculate function value and Jacobian (possibly via FD).
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203 if (has_jac)
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204 [fvec, fjac] = fcn (reshape (x, xsiz));
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205 ## If the jacobian is sparse, disable Broyden updating.
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206 if (issparse (fjac))
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207 updating = false;
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208 endif
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209 fvec = fvec(:);
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210 nfev ++;
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211 else
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212 fjac = __fdjac__ (fcn, reshape (x, xsiz), fvec, cdif);
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213 nfev += (1 + cdif) * length (x);
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214 endif
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215
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216 ## For square and overdetermined systems, we update a QR
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217 ## factorization of the jacobian to avoid solving a full system in each
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218 ## step. In this case, we pass a triangular matrix to __dogleg__.
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219 useqr = updating && m >= n && n > 10;
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220
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221 if (useqr)
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222 ## FIXME: Currently, pivoting is mostly useless because the \ operator
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223 ## cannot exploit the resulting props of the triangular factor.
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224 ## Unpivoted QR is significantly faster so it doesn't seem right to pivot
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225 ## just to get invariance. Original MINPACK didn't pivot either, at least
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226 ## when qr updating was used.
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227 [q, r] = qr (fjac, 0);
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228 endif
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229
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230 ## Get column norms, use them as scaling factors.
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231 jcn = norm (fjac, 'columns').';
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232 if (niter == 1)
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233 dg = jcn;
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234 dg(dg == 0) = 1;
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235 xn = norm (dg .* x);
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236 ## FIXME: something better?
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237 delta = factor * max (xn, 1);
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238 endif
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239
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240 ## Rescale adaptively.
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241 ## FIXME: the original minpack used the following rescaling strategy:
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242 ## dg = max (dg, jcn);
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243 ## but it seems not good if we start with a bad guess yielding jacobian
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244 ## columns with large norms that later decrease, because the corresponding
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245 ## variable will still be overscaled. So instead, we only give the old
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246 ## scaling a small momentum, but do not honor it.
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247
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248 dg = max (0.1*dg, jcn);
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249
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250 ## It also seems that in the case of fast (and inhomogeneously) changing
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251 ## jacobian, the Broyden updates are of little use, so maybe we could
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252 ## skip them if a big disproportional change is expected. The question is,
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253 ## of course, how to define the above terms :)
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254
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255 lastratio = 0;
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256 nfail = 0;
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257 nsuc = 0;
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258 decfac = 0.5;
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259
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260 ## Inner loop.
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261 while (niter <= maxiter && nfev < maxfev && ! info)
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262
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263 ## Get trust-region model (dogleg) minimizer.
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264 if (useqr)
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265 qtf = q'*fvec;
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266 s = - __dogleg__ (r, qtf, dg, delta);
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267 w = qtf + r * s;
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268 else
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269 s = - __dogleg__ (fjac, fvec, dg, delta);
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270 w = fvec + fjac * s;
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271 endif
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272
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273 sn = norm (dg .* s);
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274 if (niter == 1)
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275 delta = min (delta, sn);
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276 endif
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277
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278 fvec1 = fcn (reshape (x + s, xsiz)) (:);
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279 fn1 = norm (fvec1);
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280 nfev ++;
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281
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282 if (fn1 < fn)
8507
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283 ## Scaled actual reduction.
8306
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284 actred = 1 - (fn1/fn)^2;
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285 else
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diff changeset
286 actred = -1;
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diff changeset
287 endif
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diff changeset
288
8507
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diff changeset
289 ## Scaled predicted reduction, and ratio.
8306
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290 t = norm (w);
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diff changeset
291 if (t < fn)
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diff changeset
292 prered = 1 - (t/fn)^2;
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diff changeset
293 ratio = actred / prered;
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diff changeset
294 else
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diff changeset
295 prered = 0;
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diff changeset
296 ratio = 0;
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diff changeset
297 endif
43795cf108d0 initial implementation of fsolve
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parents:
diff changeset
298
8507
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diff changeset
299 ## Update delta.
9207
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diff changeset
300 if (ratio < min(max(0.1, 0.8*lastratio), 0.9))
8306
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diff changeset
301 nsuc = 0;
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302 nfail ++;
9207
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diff changeset
303 delta *= decfac;
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diff changeset
304 decfac ^= 1.4142;
8590
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diff changeset
305 if (delta <= 1e1*macheps*xn)
8507
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diff changeset
306 ## Trust region became uselessly small.
8306
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diff changeset
307 info = -3;
43795cf108d0 initial implementation of fsolve
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parents:
diff changeset
308 break;
43795cf108d0 initial implementation of fsolve
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parents:
diff changeset
309 endif
43795cf108d0 initial implementation of fsolve
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parents:
diff changeset
310 else
8986
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diff changeset
311 lastratio = ratio;
9207
25f50d2d76b3 improve TR updating strategy for fminunc and fsolve
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diff changeset
312 decfac = 0.5;
8306
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313 nfail = 0;
43795cf108d0 initial implementation of fsolve
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diff changeset
314 nsuc ++;
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315 if (abs (1-ratio) <= 0.1)
9207
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diff changeset
316 delta = 1.4142*sn;
8306
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317 elseif (ratio >= 0.5 || nsuc > 1)
9207
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diff changeset
318 delta = max (delta, 1.4142*sn);
8306
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319 endif
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diff changeset
320 endif
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parents:
diff changeset
321
43795cf108d0 initial implementation of fsolve
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parents:
diff changeset
322 if (ratio >= 1e-4)
8507
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diff changeset
323 ## Successful iteration.
8395
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diff changeset
324 x += s;
8306
43795cf108d0 initial implementation of fsolve
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diff changeset
325 xn = norm (dg .* x);
43795cf108d0 initial implementation of fsolve
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parents:
diff changeset
326 fvec = fvec1;
43795cf108d0 initial implementation of fsolve
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parents:
diff changeset
327 fn = fn1;
8986
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diff changeset
328 nsuciter ++;
8306
43795cf108d0 initial implementation of fsolve
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diff changeset
329 endif
43795cf108d0 initial implementation of fsolve
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parents:
diff changeset
330
8857
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diff changeset
331 niter ++;
20589a8f1a33 fix fsolve bug
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parents: 8763
diff changeset
332
8590
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diff changeset
333 ## FIXME: should outputfcn be only called after a successful iteration?
8615
7baacb6a8a65 fix typo in fsolve
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parents: 8613
diff changeset
334 if (! isempty (outfcn))
8590
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diff changeset
335 optimvalues.iter = niter;
c136d313206a improvements to fsolve
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diff changeset
336 optimvalues.funccount = nfev;
c136d313206a improvements to fsolve
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diff changeset
337 optimvalues.fval = fn;
c136d313206a improvements to fsolve
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diff changeset
338 optimvalues.searchdirection = s;
c136d313206a improvements to fsolve
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diff changeset
339 state = 'iter';
c136d313206a improvements to fsolve
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diff changeset
340 stop = outfcn (x, optimvalues, state);
c136d313206a improvements to fsolve
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diff changeset
341 if (stop)
c136d313206a improvements to fsolve
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diff changeset
342 info = -1;
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diff changeset
343 break;
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diff changeset
344 endif
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diff changeset
345 endif
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diff changeset
346
8466
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diff changeset
347 ## Tests for termination conditions. A mysterious place, anything
4d008d9f0ccf fsolve.m: style fixes
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diff changeset
348 ## can happen if you change something here...
8306
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parents:
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349
8466
4d008d9f0ccf fsolve.m: style fixes
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diff changeset
350 ## The rule of thumb (which I'm not sure M*b is quite following)
4d008d9f0ccf fsolve.m: style fixes
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diff changeset
351 ## is that for a tolerance that depends on scaling, only 0 makes
4d008d9f0ccf fsolve.m: style fixes
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diff changeset
352 ## sense as a default value. But 0 usually means uselessly long
4d008d9f0ccf fsolve.m: style fixes
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diff changeset
353 ## iterations, so we need scaling-independent tolerances wherever
4d008d9f0ccf fsolve.m: style fixes
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diff changeset
354 ## possible.
8306
43795cf108d0 initial implementation of fsolve
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parents:
diff changeset
355
8466
4d008d9f0ccf fsolve.m: style fixes
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diff changeset
356 ## FIXME -- why tolf*n*xn? If abs (e) ~ abs(x) * eps is a vector
4d008d9f0ccf fsolve.m: style fixes
John W. Eaton <jwe@octave.org>
parents: 8395
diff changeset
357 ## of perturbations of x, then norm (fjac*e) <= eps*n*xn, i.e. by
4d008d9f0ccf fsolve.m: style fixes
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diff changeset
358 ## tolf ~ eps we demand as much accuracy as we can expect.
8306
43795cf108d0 initial implementation of fsolve
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parents:
diff changeset
359 if (fn <= tolf*n*xn)
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diff changeset
360 info = 1;
8466
4d008d9f0ccf fsolve.m: style fixes
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diff changeset
361 ## The following tests done only after successful step.
9075
7b35d3b21c1c fix test in fsolve
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diff changeset
362 elseif (ratio >= 1e-4)
8466
4d008d9f0ccf fsolve.m: style fixes
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diff changeset
363 ## This one is classic. Note that we use scaled variables again,
4d008d9f0ccf fsolve.m: style fixes
John W. Eaton <jwe@octave.org>
parents: 8395
diff changeset
364 ## but compare to scaled step, so nothing bad.
8395
88fd356b0d95 optionally allow pivoting in fsolve
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parents: 8383
diff changeset
365 if (sn <= tolx*xn)
8306
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diff changeset
366 info = 2;
8466
4d008d9f0ccf fsolve.m: style fixes
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diff changeset
367 ## Again a classic one. It seems weird to use the same tolf
4d008d9f0ccf fsolve.m: style fixes
John W. Eaton <jwe@octave.org>
parents: 8395
diff changeset
368 ## for two different tests, but that's what M*b manual appears
4d008d9f0ccf fsolve.m: style fixes
John W. Eaton <jwe@octave.org>
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diff changeset
369 ## to say.
8306
43795cf108d0 initial implementation of fsolve
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parents:
diff changeset
370 elseif (actred < tolf)
8383
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diff changeset
371 info = 3;
8306
43795cf108d0 initial implementation of fsolve
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parents:
diff changeset
372 endif
43795cf108d0 initial implementation of fsolve
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parents:
diff changeset
373 endif
43795cf108d0 initial implementation of fsolve
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parents:
diff changeset
374
8507
cadc73247d65 style fixes
John W. Eaton <jwe@octave.org>
parents: 8468
diff changeset
375 ## Criterion for recalculating jacobian.
8986
22c8272af34b improvements to fsolve & family
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diff changeset
376 if (! updating || nfail == 2 || nsuciter < 2)
8306
43795cf108d0 initial implementation of fsolve
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parents:
diff changeset
377 break;
43795cf108d0 initial implementation of fsolve
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parents:
diff changeset
378 endif
43795cf108d0 initial implementation of fsolve
Jaroslav Hajek <highegg@gmail.com>
parents:
diff changeset
379
8507
cadc73247d65 style fixes
John W. Eaton <jwe@octave.org>
parents: 8468
diff changeset
380 ## Compute the scaled Broyden update.
8590
c136d313206a improvements to fsolve
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diff changeset
381 if (useqr)
c136d313206a improvements to fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8562
diff changeset
382 u = (fvec1 - q*w) / sn;
c136d313206a improvements to fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8562
diff changeset
383 v = dg .* ((dg .* s) / sn);
c136d313206a improvements to fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8562
diff changeset
384
c136d313206a improvements to fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8562
diff changeset
385 ## Update the QR factorization.
c136d313206a improvements to fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8562
diff changeset
386 [q, r] = qrupdate (q, r, u, v);
c136d313206a improvements to fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8562
diff changeset
387 else
c136d313206a improvements to fsolve
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parents: 8562
diff changeset
388 u = (fvec1 - w);
c136d313206a improvements to fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8562
diff changeset
389 v = dg .* ((dg .* s) / sn);
c136d313206a improvements to fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8562
diff changeset
390
c136d313206a improvements to fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8562
diff changeset
391 ## update the jacobian
c136d313206a improvements to fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8562
diff changeset
392 fjac += u * v';
8395
88fd356b0d95 optionally allow pivoting in fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8383
diff changeset
393 endif
8306
43795cf108d0 initial implementation of fsolve
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parents:
diff changeset
394 endwhile
43795cf108d0 initial implementation of fsolve
Jaroslav Hajek <highegg@gmail.com>
parents:
diff changeset
395 endwhile
43795cf108d0 initial implementation of fsolve
Jaroslav Hajek <highegg@gmail.com>
parents:
diff changeset
396
8507
cadc73247d65 style fixes
John W. Eaton <jwe@octave.org>
parents: 8468
diff changeset
397 ## Restore original shapes.
8306
43795cf108d0 initial implementation of fsolve
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parents:
diff changeset
398 x = reshape (x, xsiz);
43795cf108d0 initial implementation of fsolve
Jaroslav Hajek <highegg@gmail.com>
parents:
diff changeset
399 fvec = reshape (fvec, fsiz);
43795cf108d0 initial implementation of fsolve
Jaroslav Hajek <highegg@gmail.com>
parents:
diff changeset
400
43795cf108d0 initial implementation of fsolve
Jaroslav Hajek <highegg@gmail.com>
parents:
diff changeset
401 output.iterations = niter;
8986
22c8272af34b improvements to fsolve & family
Jaroslav Hajek <highegg@gmail.com>
parents: 8857
diff changeset
402 output.successful = nsuciter;
8590
c136d313206a improvements to fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8562
diff changeset
403 output.funcCount = nfev;
8306
43795cf108d0 initial implementation of fsolve
Jaroslav Hajek <highegg@gmail.com>
parents:
diff changeset
404
43795cf108d0 initial implementation of fsolve
Jaroslav Hajek <highegg@gmail.com>
parents:
diff changeset
405 endfunction
43795cf108d0 initial implementation of fsolve
Jaroslav Hajek <highegg@gmail.com>
parents:
diff changeset
406
8466
4d008d9f0ccf fsolve.m: style fixes
John W. Eaton <jwe@octave.org>
parents: 8395
diff changeset
407 ## An assistant function that evaluates a function handle and checks for
4d008d9f0ccf fsolve.m: style fixes
John W. Eaton <jwe@octave.org>
parents: 8395
diff changeset
408 ## bad results.
8693
e5ffb52c9c61 improve fsolve and add ComplexEqn option
Jaroslav Hajek <highegg@gmail.com>
parents: 8661
diff changeset
409 function [fx, jx] = guarded_eval (fun, x, complexeqn)
e5ffb52c9c61 improve fsolve and add ComplexEqn option
Jaroslav Hajek <highegg@gmail.com>
parents: 8661
diff changeset
410 if (nargout > 1)
e5ffb52c9c61 improve fsolve and add ComplexEqn option
Jaroslav Hajek <highegg@gmail.com>
parents: 8661
diff changeset
411 [fx, jx] = fun (x);
e5ffb52c9c61 improve fsolve and add ComplexEqn option
Jaroslav Hajek <highegg@gmail.com>
parents: 8661
diff changeset
412 else
e5ffb52c9c61 improve fsolve and add ComplexEqn option
Jaroslav Hajek <highegg@gmail.com>
parents: 8661
diff changeset
413 fx = fun (x);
8997
187a9d9c2f04 simplifications to fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8991
diff changeset
414 jx = [];
8693
e5ffb52c9c61 improve fsolve and add ComplexEqn option
Jaroslav Hajek <highegg@gmail.com>
parents: 8661
diff changeset
415 endif
e5ffb52c9c61 improve fsolve and add ComplexEqn option
Jaroslav Hajek <highegg@gmail.com>
parents: 8661
diff changeset
416
8997
187a9d9c2f04 simplifications to fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8991
diff changeset
417 if (! complexeqn && ! (isreal (fx) && isreal (jx)))
8468
866492035ecf fsolve.m, fzero.m: undo part of previous change
John W. Eaton <jwe@octave.org>
parents: 8467
diff changeset
418 error ("fsolve:notreal", "fsolve: non-real value encountered");
8997
187a9d9c2f04 simplifications to fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8991
diff changeset
419 elseif (complexeqn && ! (isnumeric (fx) && isnumeric(jx)))
8693
e5ffb52c9c61 improve fsolve and add ComplexEqn option
Jaroslav Hajek <highegg@gmail.com>
parents: 8661
diff changeset
420 error ("fsolve:notnum", "fsolve: non-numeric value encountered");
e5ffb52c9c61 improve fsolve and add ComplexEqn option
Jaroslav Hajek <highegg@gmail.com>
parents: 8661
diff changeset
421 elseif (any (isnan (fx(:))))
8468
866492035ecf fsolve.m, fzero.m: undo part of previous change
John W. Eaton <jwe@octave.org>
parents: 8467
diff changeset
422 error ("fsolve:isnan", "fsolve: NaN value encountered");
8306
43795cf108d0 initial implementation of fsolve
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parents:
diff changeset
423 endif
43795cf108d0 initial implementation of fsolve
Jaroslav Hajek <highegg@gmail.com>
parents:
diff changeset
424 endfunction
43795cf108d0 initial implementation of fsolve
Jaroslav Hajek <highegg@gmail.com>
parents:
diff changeset
425
43795cf108d0 initial implementation of fsolve
Jaroslav Hajek <highegg@gmail.com>
parents:
diff changeset
426 %!function retval = f (p)
43795cf108d0 initial implementation of fsolve
Jaroslav Hajek <highegg@gmail.com>
parents:
diff changeset
427 %! x = p(1);
43795cf108d0 initial implementation of fsolve
Jaroslav Hajek <highegg@gmail.com>
parents:
diff changeset
428 %! y = p(2);
43795cf108d0 initial implementation of fsolve
Jaroslav Hajek <highegg@gmail.com>
parents:
diff changeset
429 %! z = p(3);
43795cf108d0 initial implementation of fsolve
Jaroslav Hajek <highegg@gmail.com>
parents:
diff changeset
430 %! retval = zeros (3, 1);
43795cf108d0 initial implementation of fsolve
Jaroslav Hajek <highegg@gmail.com>
parents:
diff changeset
431 %! retval(1) = sin(x) + y**2 + log(z) - 7;
43795cf108d0 initial implementation of fsolve
Jaroslav Hajek <highegg@gmail.com>
parents:
diff changeset
432 %! retval(2) = 3*x + 2**y -z**3 + 1;
43795cf108d0 initial implementation of fsolve
Jaroslav Hajek <highegg@gmail.com>
parents:
diff changeset
433 %! retval(3) = x + y + z - 5;
43795cf108d0 initial implementation of fsolve
Jaroslav Hajek <highegg@gmail.com>
parents:
diff changeset
434 %!test
43795cf108d0 initial implementation of fsolve
Jaroslav Hajek <highegg@gmail.com>
parents:
diff changeset
435 %! x_opt = [ 0.599054;
43795cf108d0 initial implementation of fsolve
Jaroslav Hajek <highegg@gmail.com>
parents:
diff changeset
436 %! 2.395931;
43795cf108d0 initial implementation of fsolve
Jaroslav Hajek <highegg@gmail.com>
parents:
diff changeset
437 %! 2.005014 ];
43795cf108d0 initial implementation of fsolve
Jaroslav Hajek <highegg@gmail.com>
parents:
diff changeset
438 %! tol = 1.0e-5;
43795cf108d0 initial implementation of fsolve
Jaroslav Hajek <highegg@gmail.com>
parents:
diff changeset
439 %! [x, fval, info] = fsolve (@f, [ 0.5; 2.0; 2.5 ]);
43795cf108d0 initial implementation of fsolve
Jaroslav Hajek <highegg@gmail.com>
parents:
diff changeset
440 %! assert (info > 0);
8383
a762d9daa700 allow overdetermined systems in fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8306
diff changeset
441 %! assert (norm (x - x_opt, Inf) < tol);
8306
43795cf108d0 initial implementation of fsolve
Jaroslav Hajek <highegg@gmail.com>
parents:
diff changeset
442 %! assert (norm (fval) < tol);
43795cf108d0 initial implementation of fsolve
Jaroslav Hajek <highegg@gmail.com>
parents:
diff changeset
443
43795cf108d0 initial implementation of fsolve
Jaroslav Hajek <highegg@gmail.com>
parents:
diff changeset
444 %!function retval = f (p)
43795cf108d0 initial implementation of fsolve
Jaroslav Hajek <highegg@gmail.com>
parents:
diff changeset
445 %! x = p(1);
43795cf108d0 initial implementation of fsolve
Jaroslav Hajek <highegg@gmail.com>
parents:
diff changeset
446 %! y = p(2);
43795cf108d0 initial implementation of fsolve
Jaroslav Hajek <highegg@gmail.com>
parents:
diff changeset
447 %! z = p(3);
43795cf108d0 initial implementation of fsolve
Jaroslav Hajek <highegg@gmail.com>
parents:
diff changeset
448 %! w = p(4);
43795cf108d0 initial implementation of fsolve
Jaroslav Hajek <highegg@gmail.com>
parents:
diff changeset
449 %! retval = zeros (4, 1);
43795cf108d0 initial implementation of fsolve
Jaroslav Hajek <highegg@gmail.com>
parents:
diff changeset
450 %! retval(1) = 3*x + 4*y + exp (z + w) - 1.007;
43795cf108d0 initial implementation of fsolve
Jaroslav Hajek <highegg@gmail.com>
parents:
diff changeset
451 %! retval(2) = 6*x - 4*y + exp (3*z + w) - 11;
43795cf108d0 initial implementation of fsolve
Jaroslav Hajek <highegg@gmail.com>
parents:
diff changeset
452 %! retval(3) = x^4 - 4*y^2 + 6*z - 8*w - 20;
43795cf108d0 initial implementation of fsolve
Jaroslav Hajek <highegg@gmail.com>
parents:
diff changeset
453 %! retval(4) = x^2 + 2*y^3 + z - w - 4;
43795cf108d0 initial implementation of fsolve
Jaroslav Hajek <highegg@gmail.com>
parents:
diff changeset
454 %!test
43795cf108d0 initial implementation of fsolve
Jaroslav Hajek <highegg@gmail.com>
parents:
diff changeset
455 %! x_opt = [ -0.767297326653401, 0.590671081117440, 1.47190018629642, -1.52719341133957 ];
43795cf108d0 initial implementation of fsolve
Jaroslav Hajek <highegg@gmail.com>
parents:
diff changeset
456 %! tol = 1.0e-5;
43795cf108d0 initial implementation of fsolve
Jaroslav Hajek <highegg@gmail.com>
parents:
diff changeset
457 %! [x, fval, info] = fsolve (@f, [-1, 1, 2, -1]);
43795cf108d0 initial implementation of fsolve
Jaroslav Hajek <highegg@gmail.com>
parents:
diff changeset
458 %! assert (info > 0);
8383
a762d9daa700 allow overdetermined systems in fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8306
diff changeset
459 %! assert (norm (x - x_opt, Inf) < tol);
8306
43795cf108d0 initial implementation of fsolve
Jaroslav Hajek <highegg@gmail.com>
parents:
diff changeset
460 %! assert (norm (fval) < tol);
8383
a762d9daa700 allow overdetermined systems in fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8306
diff changeset
461
a762d9daa700 allow overdetermined systems in fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8306
diff changeset
462 %!function retval = f (p)
a762d9daa700 allow overdetermined systems in fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8306
diff changeset
463 %! x = p(1);
a762d9daa700 allow overdetermined systems in fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8306
diff changeset
464 %! y = p(2);
a762d9daa700 allow overdetermined systems in fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8306
diff changeset
465 %! z = p(3);
a762d9daa700 allow overdetermined systems in fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8306
diff changeset
466 %! retval = zeros (3, 1);
a762d9daa700 allow overdetermined systems in fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8306
diff changeset
467 %! retval(1) = sin(x) + y**2 + log(z) - 7;
a762d9daa700 allow overdetermined systems in fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8306
diff changeset
468 %! retval(2) = 3*x + 2**y -z**3 + 1;
a762d9daa700 allow overdetermined systems in fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8306
diff changeset
469 %! retval(3) = x + y + z - 5;
a762d9daa700 allow overdetermined systems in fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8306
diff changeset
470 %! retval(4) = x*x + y - z*log(z) - 1.36;
a762d9daa700 allow overdetermined systems in fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8306
diff changeset
471 %!test
a762d9daa700 allow overdetermined systems in fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8306
diff changeset
472 %! x_opt = [ 0.599054;
a762d9daa700 allow overdetermined systems in fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8306
diff changeset
473 %! 2.395931;
a762d9daa700 allow overdetermined systems in fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8306
diff changeset
474 %! 2.005014 ];
a762d9daa700 allow overdetermined systems in fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8306
diff changeset
475 %! tol = 1.0e-5;
8590
c136d313206a improvements to fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8562
diff changeset
476 %! [x, fval, info] = fsolve (@f, [ 0.5; 2.0; 2.5 ]);
8383
a762d9daa700 allow overdetermined systems in fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8306
diff changeset
477 %! assert (info > 0);
a762d9daa700 allow overdetermined systems in fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8306
diff changeset
478 %! assert (norm (x - x_opt, Inf) < tol);
a762d9daa700 allow overdetermined systems in fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8306
diff changeset
479 %! assert (norm (fval) < tol);
a762d9daa700 allow overdetermined systems in fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8306
diff changeset
480
8395
88fd356b0d95 optionally allow pivoting in fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8383
diff changeset
481 %!function retval = f (p)
88fd356b0d95 optionally allow pivoting in fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8383
diff changeset
482 %! x = p(1);
88fd356b0d95 optionally allow pivoting in fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8383
diff changeset
483 %! y = p(2);
88fd356b0d95 optionally allow pivoting in fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8383
diff changeset
484 %! z = p(3);
88fd356b0d95 optionally allow pivoting in fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8383
diff changeset
485 %! retval = zeros (3, 1);
88fd356b0d95 optionally allow pivoting in fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8383
diff changeset
486 %! retval(1) = sin(x) + y**2 + log(z) - 7;
88fd356b0d95 optionally allow pivoting in fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8383
diff changeset
487 %! retval(2) = 3*x + 2**y -z**3 + 1;
88fd356b0d95 optionally allow pivoting in fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8383
diff changeset
488 %! retval(3) = x + y + z - 5;
88fd356b0d95 optionally allow pivoting in fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8383
diff changeset
489 %!test
88fd356b0d95 optionally allow pivoting in fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8383
diff changeset
490 %! x_opt = [ 0.599054;
88fd356b0d95 optionally allow pivoting in fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8383
diff changeset
491 %! 2.395931;
88fd356b0d95 optionally allow pivoting in fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8383
diff changeset
492 %! 2.005014 ];
88fd356b0d95 optionally allow pivoting in fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8383
diff changeset
493 %! tol = 1.0e-5;
8590
c136d313206a improvements to fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8562
diff changeset
494 %! opt = optimset ("Updating", "qrp");
8395
88fd356b0d95 optionally allow pivoting in fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8383
diff changeset
495 %! [x, fval, info] = fsolve (@f, [ 0.5; 2.0; 2.5 ], opt);
88fd356b0d95 optionally allow pivoting in fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8383
diff changeset
496 %! assert (info > 0);
88fd356b0d95 optionally allow pivoting in fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8383
diff changeset
497 %! assert (norm (x - x_opt, Inf) < tol);
88fd356b0d95 optionally allow pivoting in fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8383
diff changeset
498 %! assert (norm (fval) < tol);
8590
c136d313206a improvements to fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8562
diff changeset
499
c136d313206a improvements to fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8562
diff changeset
500 %!test
c136d313206a improvements to fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8562
diff changeset
501 %! b0 = 3;
c136d313206a improvements to fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8562
diff changeset
502 %! a0 = 0.2;
c136d313206a improvements to fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8562
diff changeset
503 %! x = 0:.5:5;
c136d313206a improvements to fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8562
diff changeset
504 %! noise = 1e-5 * sin (100*x);
c136d313206a improvements to fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8562
diff changeset
505 %! y = exp (-a0*x) + b0 + noise;
c136d313206a improvements to fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8562
diff changeset
506 %! c_opt = [a0, b0];
c136d313206a improvements to fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8562
diff changeset
507 %! tol = 1e-5;
c136d313206a improvements to fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8562
diff changeset
508 %!
c136d313206a improvements to fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8562
diff changeset
509 %! [c, fval, info, output] = fsolve (@(c) (exp(-c(1)*x) + c(2) - y), [0, 0]);
c136d313206a improvements to fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8562
diff changeset
510 %! assert (info > 0);
c136d313206a improvements to fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8562
diff changeset
511 %! assert (norm (c - c_opt, Inf) < tol);
c136d313206a improvements to fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8562
diff changeset
512 %! assert (norm (fval) < norm (noise));
c136d313206a improvements to fsolve
Jaroslav Hajek <highegg@gmail.com>
parents: 8562
diff changeset
513
8693
e5ffb52c9c61 improve fsolve and add ComplexEqn option
Jaroslav Hajek <highegg@gmail.com>
parents: 8661
diff changeset
514
e5ffb52c9c61 improve fsolve and add ComplexEqn option
Jaroslav Hajek <highegg@gmail.com>
parents: 8661
diff changeset
515 %!function y = cfun (x)
e5ffb52c9c61 improve fsolve and add ComplexEqn option
Jaroslav Hajek <highegg@gmail.com>
parents: 8661
diff changeset
516 %! y(1) = (1+i)*x(1)^2 - (1-i)*x(2) - 2;
e5ffb52c9c61 improve fsolve and add ComplexEqn option
Jaroslav Hajek <highegg@gmail.com>
parents: 8661
diff changeset
517 %! y(2) = sqrt (x(1)*x(2)) - (1-2i)*x(3) + (3-4i);
e5ffb52c9c61 improve fsolve and add ComplexEqn option
Jaroslav Hajek <highegg@gmail.com>
parents: 8661
diff changeset
518 %! y(3) = x(1) * x(2) - x(3)^2 + (3+2i);
e5ffb52c9c61 improve fsolve and add ComplexEqn option
Jaroslav Hajek <highegg@gmail.com>
parents: 8661
diff changeset
519
e5ffb52c9c61 improve fsolve and add ComplexEqn option
Jaroslav Hajek <highegg@gmail.com>
parents: 8661
diff changeset
520 %!test
e5ffb52c9c61 improve fsolve and add ComplexEqn option
Jaroslav Hajek <highegg@gmail.com>
parents: 8661
diff changeset
521 %! x_opt = [-1+i, 1-i, 2+i];
e5ffb52c9c61 improve fsolve and add ComplexEqn option
Jaroslav Hajek <highegg@gmail.com>
parents: 8661
diff changeset
522 %! x = [i, 1, 1+i];
e5ffb52c9c61 improve fsolve and add ComplexEqn option
Jaroslav Hajek <highegg@gmail.com>
parents: 8661
diff changeset
523 %!
e5ffb52c9c61 improve fsolve and add ComplexEqn option
Jaroslav Hajek <highegg@gmail.com>
parents: 8661
diff changeset
524 %! [x, f, info] = fsolve (@cfun, x, optimset ("ComplexEqn", "on"));
e5ffb52c9c61 improve fsolve and add ComplexEqn option
Jaroslav Hajek <highegg@gmail.com>
parents: 8661
diff changeset
525 %! tol = 1e-5;
e5ffb52c9c61 improve fsolve and add ComplexEqn option
Jaroslav Hajek <highegg@gmail.com>
parents: 8661
diff changeset
526 %! assert (norm (f) < tol);
e5ffb52c9c61 improve fsolve and add ComplexEqn option
Jaroslav Hajek <highegg@gmail.com>
parents: 8661
diff changeset
527 %! assert (norm (x - x_opt, Inf) < tol);
e5ffb52c9c61 improve fsolve and add ComplexEqn option
Jaroslav Hajek <highegg@gmail.com>
parents: 8661
diff changeset
528