std.m

一些用matlab编写的经典遗传算法算例 挺有用的

function dev = std(chr)
% STD - Standard deviation 
%    For vectors, STD(chr) returns the standard
%    deviation of the population. For matrices, STD(chr) is a column vector
%    containing the standard deviation of each row.  
% 
%    STD(chr) normalizes by (N-1) where N is the sequence length.  This
%    makes STD(X).^2 the best unbiased estimate of the variance if X
%    is a sample from a normal distribution.
% 
% See Also MAX,MIN,MEAN,MEDIAN
[m n]=size(chr);
for k=1:m
  for l=1:n
    fit(l)=get(chr(k,l),'fitness');
  end
  dev(k,1)=std(fit);
end