Hi Dear

Dear Sanat,

I'm looking for the same function as you, but I don't find anything so far. Did you find a solution to you problem since you asked your question? Here is a code that I built to compute the "radial" average of 3D data with matlab. I'm not completely sure of myself so I'd be happy to have some feedback.

function fTr = radialspectrum3D(F,d)

%fTr computes the radial avareage of the 3D power spectral density of F.

%d is the size of the voxels in m.

%the three dimensions of F are supposed to be equal.

s = size(F);

dim = s(1);

fT = fftshift((abs(fftn(fftshift(F))).^2))/dim^6;

fTr = zeros(1,floor((dim)/2));

for r = 0:(dim)/2-1

    R = (r+1)*pi*2/d/dim;

    for j =1:dim

        for k =1:dim

            for l = 1:dim

                if (j-(dim)/2-1)^2+(k-(dim)/2-1)^2+(l-(dim)/2-1)^2 >= r^2 && (j-(dim)/2-1)^2+(k-(dim)/2-1)^2+(l-(dim)/2-1)^2 < (r+1)^2

                    fTr(r+1) = fTr(r+1)+fT(j,k,l)/4/pi/(R)^2/(pi*2/d/dim);

                end

            end

        end

    end

end

k = pi*4/d/dim:pi*2/d/dim:pi/d;

figure;

loglog(k,fTr(2:end))

xlabel('wave number (m^-^1)')

ylabel('PSD')

Dear Eric, 

Thanks for your suggestion. I too have written code. Will try to match both codes and let you know in few days as presently outside institute.