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Diffstat (limited to 'modules/statistics/macros/cmoment.sci')
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1 files changed, 57 insertions, 0 deletions
diff --git a/modules/statistics/macros/cmoment.sci b/modules/statistics/macros/cmoment.sci new file mode 100755 index 000000000..fc0b8a571 --- /dev/null +++ b/modules/statistics/macros/cmoment.sci @@ -0,0 +1,57 @@ + +// 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 |