Question

matlab中if nargin<5 options=[1e-6 1];end if nargin<4 evalOps=[];什么意思？还有这个代码作用？

function [pop] = initializega(num, bounds, evalFN,evalOps,options)
% function [pop]=initializega(populationSize, variableBounds,evalFN,
% evalOps,options)
% initializega creates a matrix of random numbers with
% a number of rows equal to the populationSize and a number
% columns equal to the number of rows in bounds plus 1 for
% the f(x) value which is found by applying the evalFN.
% This is used by the ga to create the population if it
% is not supplied.
%
% pop - the initial, evaluated, random population
% populatoinSize - the size of the population, i.e. the number to create
% variableBounds - a matrix which contains the bounds of each variable, i.e.
% [var1_high var1_low; var2_high var2_low; ....]
% evalFN - the evaluation fn, usually the name of the .m file for
% evaluation
% evalOps - any options to be passed to the eval function defaults []
% options - options to the initialize function, ie.
% [type prec] where eps is the epsilon value
% and the second option is 1 for float and 0 for binary,
% prec is the precision of the variables defaults [1e-6 1]

% Binary and Real-Valued Simulation Evolution for Matlab GAOT V2
% Copyright (C) 1998 C.R. Houck, J.A. Joines, M.G. Kay

if nargin<5
options=[1e-6 1];
end
if nargin<4
evalOps=[];
end

if any(evalFN<48) % Not a .m file
if options(2)==1 % Float GA
estr=['x=pop(i,1); pop(i,xZomeLength)=', evalFN ';'];
else % Binary GA
estr=['x=b2f(pop(i,:),bounds,bits); pop(i,xZomeLength)=', evalFN ';'];
end
else % A .m file
if options(2)==1 % Float GA
estr=['[ pop(i,:) pop(i,xZomeLength)]=' evalFN '(pop(i,:),[0 evalOps]);']
else % Binary GA
estr=['x=b2f(pop(i,:),bounds,bits);[x v]=' evalFN ...
'(x,[0 evalOps]); pop(i,:)=[f2b(x,bounds,bits) v];']
end
end

numVars = size(bounds,1); % Number of variables, size(bounds,1)return the number of 返回矩阵bounds的行数
rng = (bounds(:,2)-bounds(:,1))'; % The variable ranges'

if options(2)==1 % Float GA
xZomeLength = numVars+1; % Length of string is numVar + fit 染色体长度 = 变量数 + 适应度变量
pop = zeros(num,xZomeLength); % Allocate the new population
pop(:,1:numVars)=(ones(num,numVars)*rng).*(rand(num,numVars))+...
(ones(num,1)*bounds(:,1)');
else % Binary GA
bits=calcbits(bounds,options(1));
xZomeLength = sum(bits)+1; % Length of string is numVar + fit
pop = round(rand(num,sum(bits)+1));
end

for i=1:num
eval(estr)
end
很急啊

Answer 1

把这几句注释下：
if nargin<5 %如果输入参数少于5个时
options=[1e-6 1];%赋值
end %条件判断结束
if nargin<4 %如果输入参数少于4个时
evalOps=[];%赋空值
另外，这整段程序是用于初始化遗传算法的，就是遗传算法优化程序的预处理子程序，为后面的主程序打基础。

Answer 2

nargin是用来判断输入变量个数的函数，这样就可以针对不同的情况执行不同的功能。通常可以用他来设定一些默认值，如你上面的函数。
当nargin=5时，options=[10^(-6) 1]
当nargin=4时，evalOps=[]；

追问

那这段代码的作用是什么？可不可认识下，我还有些代码要问。

追答

就是拿来设定一些默认值的，你的整个程序我其实也没看懂，呵呵

追问

我的QQ号是543613835，可以网上聊吗

Answer 3

这段代码是用来初始化遗传算法的种群