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// Scilab ( http://www.scilab.org/ ) - This file is part of Scilab
// Copyright (C) 2008 - INRIA - Michael Baudin
//
// 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_V2.1-en.txt
//
function [s] = mtlb_var (x,w,dim)
//
// mtlb_var --
// This function computes the variance of the values of a vector or
// matrix x.
// It provides the same service as Octave and Matlab.
// Arguments
// x may be a real or a complex vector or matrix.
// s is a real scalar or real vector.
// If x is a vector, s = mtlb_var(x) is the variance of x.
// If x is a matrix, s = mtlb_var(x) is a row vector containing the variance of each column of x.
// w : type of normalization to use. Valid values are, depending on the number of columns m of x :
// w = 0 : normalizes with m-1, provides the best unbiased estimator of the variance [default].
// w = 1: normalizes with m, this provides the second moment around the mean.
// dim : the dimension along which the variance is computed (default is 1, i.e. column by column)
// If dim is 2, the variance is computed row by row.
//
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"),"mtlb_var",1,2))
end
[m n]=size(x);
if rhs == 1 then
w = 0;
end
if rhs<=2 then
dim=1;
end
if dim==1 then
if w==0 then
if m==1 then
error(msprintf(gettext("%s: The normalization m - 1 factor is zero.\n"),"mtlb_var"))
end
end
end
if dim==2 then
if w==1 then
if n==1 then
error(msprintf(gettext("%s: The normalization n - 1 factor is zero.\n"),"mtlb_var"))
end
end
end
query = warning("query");
warning("off")
if rhs == 1 | w == 0 then
s = variance(x,dim);
else
s = variance(x,dim,mean(x, dim));
end
warning(query)
endfunction
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