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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 sd=stdev(x,o)
//
//This function computes the standard deviation of the values of a
//vector or matrix x.
//
//For a vector or a matrix x, s=stdev(x) returns in the scalar s the
//standard deviation of all the entries of x.
//
//s=stdev(x,'r') (or, equivalently, s=stdev(x,1)) is the rowwise
//standard deviation. It returns in each entry of the row vector s the
//standard deviation of each column of x.
//
//s=stdev(x,'c') (or, equivalently, s=stdev(x,2)) is the columnwise
//standard deviation. It returns in each entry of the column vector y
//the standard deviation of each row of x.
//
//
if argn(2)<2 then o='*',end
if x == [] then sd=%nan;return ;end
if typeof(x)=='hypermat' then sd=%hm_st_deviation(x,o),return,end
// remove the mean
if o=='*' then
y=x - mean(x)
elseif o=='c'|o==2 then
y=x - mean(x,'c')*ones(x(1,:))
elseif o=='r'|o==1 then
y=x - ones(x(:,1))*mean(x,'r')
else
error(msprintf(gettext("%s: Wrong value for input argument #%d: ''%s'', ''%s'', ''%s'', %d or %d expected.\n"),"stdev",2,"*","c","r",1,2)),
end
if size(x,o)==1 then
sd=0*y
else
sd=sqrt(sum(y.^2,o)/(size(x,o)-1));
end
endfunction
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