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// Scilab ( http://www.scilab.org/ ) - This file is part of Scilab
// Copyright (C) 1999 - 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_V2.1-en.txt
//
function mom= cmoment(x,ord,orien)
//
//This function computes the central moment of all orders of a vector or
//matrix x.
//
//For a vector or matrix x, mom=cmoment(x,ord) returns in the scalar mom
//the moment of order ord of all the entries of x.
//
//mom=cmoment(x,ord,'r')(or, equivalently, mom=cmoment(x,ord,1)) returns
//in each entry of the row vector mom the moment of order ord of each
//column of x.
//
//mom=cmoment(x,ord,'c')(or, equivalently, mom=cmoment(x,ord,2)) returns
//in each entry of the column vector mom the moment of order ord of each
//row of x.
//
//Nota: In the calculations the divisor is n-1 , where n is the
//dimension of the data vector.
//
//References: Wonacott, T.H. & Wonacott, R.J.; Introductory
//Statistics, J.Wiley & Sons, 1990.
//
//
[lhs,rhs]=argn(0)
if rhs<2 then error(msprintf(gettext("%s: Wrong number of input arguments: %d to %d expected.\n"),"cmoment",2,3)), end
if x==[]|ord==[] then mom=%nan, return, end
if rhs==2 then
if ord==1 then mom=0, return, end
le=length(x)
m=sum(x)/le
mom=sum((x-m).^ord)/(le)
return
elseif rhs==3 then
le=size(x,orien)
m=mean(x,orien)
if orien=="r"|orien==1 then
m=m(ones(le,1),:)
elseif orien=="c"|orien==1 then
m=m(:,ones(le,1))
else error(msprintf(gettext("%s: Wrong value for input argument #%d: ''%s'', ''%s'', %d or %d expected.\n"),"cmoment",3,"r","c",1,2)),
end
mom=sum((x-m).^ord,orien)/(le)
return
else error(msprintf(gettext("%s: Wrong number of input arguments: %d to %d expected.\n"),"cmoment",2,3)),
end
endfunction
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