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// Scilab ( http://www.scilab.org/ ) - This file is part of Scilab
// Copyright (C) 2000 - INRIA - Carlos Klimann
//
// This file must be used under the terms of the CeCILL.
// This source file is licensed as described in the file COPYING, which
// you should have received as part of this distribution. The terms
// are also available at
// http://www.cecill.info/licences/Licence_CeCILL_V2-en.txt
//
function [s]=variance(x,orien,w)
//
//This function computes the variance of the values of a vector or
//matrix x.
//
//For a vector or a matrix x, s=variance(x) returns in the scalar s the
//variance of all the entries of x.
//
//s=variance(x,'r') (or, equivalently, s=variance(x,1)) is the rowwise
//variance. It returns in each entry of the row vector s the variance of
//each column of x.
//
//s=variance(x,'c') (or, equivalently, s=variance(x,2)) is the columnwise standard
//deviation. It returns in each entry of the column vector y the
//variance of each row of x.
//
//
if x==[] then
s=%nan;
return;
end
[lhs,rhs]=argn(0)
if rhs==0 then
error(msprintf(gettext("%s: Wrong number of input arguments: %d to %d expected.\n"),"variance",1,2))
end
[m n]=size(x);
if rhs<=2 then
w=0;
end
if rhs==1
if w==0 then
s=(sum((x-mean(x)).^2))/(m*n-1);
elseif w==1 then
s=(sum((x-mean(x)).^2))/(m*n);
else
error(msprintf(gettext("%s: Wrong value of w : %d; 0 or 1 expected.\n"),"variance",w))
end
elseif orien=='c'|orien==2 then
y(1:m,1:n) = x(1:m,1:n) - mean(x,2) * ones(1,n);
s = ones(m,1);
for i=1:m
s(i) = real(y(i,1:n) * y(i,1:n)');
if w==0 then
s(i) = s(i) / (n - 1);
elseif w==1 then
s(i) = s(i) / n;
else
error(msprintf(gettext("%s: Wrong value of w : %d; 0 or 1 expected.\n"),"variance",w))
end
end
elseif orien=='r'|orien==1 then
y(1:m,1:n) = x(1:m,1:n) - ones(m,1) * mean(x,1);
s = ones(1,n);
for i=1:n
s(i) = real(y(1:m,i)' * y(1:m,i));
if w==0 then
s(i) = s(i) / (m - 1);
elseif w==1 then
s(i) = s(i) / m;
else
error(msprintf(gettext("%s: Wrong value of w : %d; 0 or 1 expected.\n"),"variance",w))
end
end
else
error(msprintf(gettext("%s: Wrong value for input argument: ''%s'', ''%s'', %d or %d expected.\n"),"variance","c","r",1,2));
end
endfunction
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