samer@4: function N=pdev(p,A,D)
samer@4: % pdev - p-deviation, generalisation of stddev for exponents other than 2
samer@4: %
samer@4: % pdev :: nonneg, [[D1]], I:natural -> [[D2]].
samer@4: % pdev :: nonneg, [[N D]] -> [[ 1 D]].
samer@4: %
samer@4: % where D2 = set(D1,I,1), ie the Ith dimension is
samer@4: % collapsed. I defaults to 1. The p-deviation is defined as 
samer@4: %    pdev(p,x,i) = mean(abs(x).^p,i).^(1/p)
samer@4: %
samer@4: % See also pnorm.
samer@4: 
samer@4: if nargin<2, D=1; end;
samer@4: 
samer@4: if p==2
samer@4: 	N=sqrt(mean(abs(A).^2,D));
samer@4: else
samer@21: 	N=real(mean(abs(A).^p,D).^(1/p));
samer@4: end
samer@4: 	
samer@4: