nanstd.m

来自「matlab数字信号处理工具箱」· M 代码 · 共 46 行

function [y] = nanstd(i,DIM)
% NANSTD same as STD but ignores NaN's. 
% NANSTD is OBSOLETE; use NaN/STD instead. NANSTD is included 
%    to fix a bug in some other versions. 
%
% Y = nanstd(x [,DIM])
% 
% DIM	dimension
%	1 sum of columns
%	2 sum of rows
%	default or []: first DIMENSION with more than 1 element
% Y	resulting standard deviation
% 
% see also: SUM, SUMSKIPNAN, NANSUM, STD

%    This program is free software; you can redistribute it and/or modify
%    it under the terms of the GNU General Public License as published by
%    the Free Software Foundation; either version 2 of the License, or
%    (at your option) any later version.
%
%    This program is distributed in the hope that it will be useful,
%    but WITHOUT ANY WARRANTY; without even the implied warranty of
%    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
%    GNU General Public License for more details.
%
%    You should have received a copy of the GNU General Public License
%    along with this program; if not, write to the Free Software
%    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

%    Copyright (C) 2000-2003 by Alois Schloegl <[e-mail]>	
%	$Revision: 1.2 $
%	$Id: nanstd.m,v 1.2 2003/09/27 09:45:12 schloegl Exp $


if nargin>1
        [s,n,y] = sumskipnan(i,DIM);
else
        [s,n,y] = sumskipnan(i);
end;

y = y.*n - real(s).^2 - imag(s).^2;   % n*n * (summed squares with removed mean)

y = sqrt(y./(n.*max(n-1,0)));	% normalize