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| Syntax |
ifft2d(z) |
| See Also | fft2d , ifft |
M is the number of rows in
z and N is the number of columns in
z, the (i,j)-th
element of the return value is equal to
M N
----- ----- { __ [ (i - M/2 - 1) (m - M/2 - 1) / M ] }
> > z exp{ 2 pi \/-1 [ + ] }
----- ----- m,n { [ (j - N/2 - 1) (n - N/2 - 1) / N ] }
m = 1 n = 1
M and N are
2, 3, 5, and 7, the transform is done in order
(M)(N)[log(N) + log(M)] operations;
otherwise the transform is done in order
(M)(N)(N + M) operations.
M is 4, N is 2,
and the (4,1)-th and (4,2)-th elements of z
are one (the rest of the elements of z are zero).
The (i,j)-th element of the transform is therefore equal to
__ __
exp{2 pi \/-1 [(i - 3) / 4 - (j - 2) / 2]} + exp[2 pi \/-1 (i - 3) / 4]
z = [{0, 0, 0, 1}, {0, 0, 0, 1}]
ifft2d(z)
O-Matrix replies
{
[ (0,0) , (-2,0) ]
[ (0,0) , (0,-2) ]
[ (0,0) , (2,0) ]
[ (0,0) , (0,2) ]
}
Due to numerical limitations,
some of the zeros may be output as numbers that are nearly 0.