function [a2] = fft2d(a)
//a = any real or complex 2D matrix
//a2 = 2D-DFT of 2D matrix  'a'
m=size(a,1)
n=size(a,2)
// fourier transform along the rows
for i=1:n
a1(:,i)=exp(-2*%i*%pi*(0:m-1)'.*.(0:m-1)/m)*a(:,i)
end
// fourier transform along the columns
for j=1:m
a2temp=exp(-2*%i*%pi*(0:n-1)'.*.(0:n-1)/n)*(a1(j,:)).'
a2(j,:)=a2temp.'
end
for i = 1:m
    for j = 1:n
        if((abs(real(a2(i,j)))<0.0001)&(abs(imag(a2(i,j)))<0.0001))
            a2(i,j)=0;
        elseif(abs(real(a2(i,j)))<0.0001)
            a2(i,j)= 0+%i*imag(a2(i,j));
        elseif(abs(imag(a2(i,j)))<0.0001)
            a2(i,j)= real(a2(i,j))+0;
        end
    end
end