Documentation of rms

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Function Synopsis

y = rms(x,dim)

Help text

RMS    root-mean square. For vectors, RMS(x) returns the standard
       deviation.  For matrices, RMS(X) is a row vector containing
       the root-mean-square of each column. The difference to STD is
       that here the mean is NOT removed.  
       RMS(X,DIM) returns the root-mean-square of dimension DIM

	See also STD,COV.

	uses :	intvers.m	

Cross-Reference Information

Listing of function rms

function y = rms(x,dim)

%       Uwe Send, IfM Kiel, Apr 1992
% added NaN handling   Gerd Krahmann, IfM Kiel, Oct 1993, Jun 1994
% removed bug in NaN handling   G.Krahmann, Aug 1994
% added compatibility to MATLAB 5	G.Krahmann, LODYC Paris, Jul 1997

if intvers>4

  if nargin<2
    dim=min(find(size(x)>1));
  end

  if all(isnan(x))
    y=nan;
    return
  end    

  x = shiftdim(x,dim-1);
  s = size(x);
  so = s(1);
  s(1) = 1;

  for n = 1:prod(s)
    good = find(~isnan(x(:,n)));
    if ~isempty(good)
      y(1,n) = norm( x(good,n) ) / sqrt(length(good));
    else
      y(1,n) = NaN;
    end
  end
  y = reshape(y,s);
  y = shiftdim( y, ndims(x)-dim+1 );

else

  [m,n] = size(x);

  bad=find(isnan(x));
  if ~isempty(bad)
    if (m == 1) + (n == 1)
      x=x(find(~isnan(x)));
      [m,n] = size(x);
      if isempty(x)
        y=nan;
        return
      end
    end
  end    
  

  if (m == 1) + (n == 1)
	m = max(m,n);
        y = norm(x);
	y = y / sqrt(m);
  else
	y = zeros(1,n);
	for i=1:n
                y(i) = rms(x(:,i));
	end
  end

end