Not sure what this line of code is doing

Question

John 2015-12-27

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/261696-not-sure-what-this-line-of-code-is-doing

回答： Walter Roberson 2015-12-27

I'm trying to translate the following Matlab code into R, and I'm not sure what line 45 is doing. Can someone explain to me what's going on here? How are variable values being assigned? What is fminserach doing?

[R,fval,outf,op]=fminsearch(@(params) eglike(params,data),pinit,optionsfmin);

It's a part of this larger script:

function R=egfit(data, params, options)
% version 2.2 27/02/07
% uses fminsearch instead of fmins
% (c) Yves Lacouture, Universite Laval
[n,m]=size(data);
if min(n,m) > 1
   error('First argument must be a vector');
end
if  n == 1                             %case of a row vector of data
  data = data';
  n = m;
end
if min(data)<=0                       % get rid of zeros and negative numbers
  warning('data include zero(s) and/or negative number(s)');
  nc=length(find(data<=0));
  fprintf('%d values out of %d are truncated\n', nc, n);
  data=data(find(data>0));
end
if  (nargin > 1 & ~isempty(params))   % explicit starting parameter values set by user
  mu=params(1);
  sig=params(2);
  tau=params(3);
else    
  tau=std(data).*0.8;            % set defaut starting parameter values if not explicit
  mu=mean(data)-tau;                % uses heuristic values
  sig=sqrt(var(data)-(tau^2));
end
if  (nargin > 2 & ~isempty(options))  % explicit options values set by user and pass to fmins
  opts(1:3)=options(1:3);           % termination, function tolerances and maximum number of iterations
                
else
  opts=[ 1.e-4,1.e-4];            % default values for termination and function tolerances
    opts(3)=200*length(data);         % default max number of iterations
end
%optionsfmin=optimset('TolX',opts(1),'TolFun',opts(2),'MaxIter',opts(3));
% was in version 2.2; should be MaxFunEvals
optionsfmin=optimset('TolX',opts(1),'TolFun',opts(2),'MaxFunEvals',opts(3));
pinit  = [mu sig tau];                % put initial parameter values in an array
% [R,opt] = fmins('eglike',pinit,opts,[],data);  % based on old function fmins
[R,fval,outf,op]=fminsearch(@(params) eglike(params,data),pinit,optionsfmin);
if (outf<1) 
    disp(op) 
end