function [y,xm,ys] = mediannan(x,na)

%MEDIAN	Median value. ignor NAN values

%	For vectors,  MEDIAN(X)  is the median value of the elements in X.

%	For matrices, MEDIAN(X) is a row vector containing the median value

%	of each column.

%

%       average over -na:na central points

%       M. Visbeck

%	Copyright (c) 1984-94 by The MathWorks, Inc.

if nargin<2, na=0; end

na=fix(na);

[m,n] = size(x);

if (m==1)

   x=x.';

end 

[m,n] = size(x);

xm=x+NaN;

for i=1:n

  ii=find(isfinite(x(:,i)));

  if length(ii)>0

    xs=sort(x(ii,i)); 

    indexav=round([-na:na] + length(xs)/2);

    ii=find(indexav>0 & indexav<=length(xs));

    indexav=indexav(ii);

    xm(indexav,i) = xs(indexav);

    y(i)=mean(xs(indexav));

    ys(i)=std(xs(indexav));

  else

   ys(i)=NaN;

   y(i)=NaN;

  end

end