Figure Properties - SERC

2ifft2
Purpose Two-dimensional inverse discrete Fourier transform
Syntax Y = ifft2(X)
Y = ifft2(X,m,n)
y = ifft2(..., 'nonsymmetric')
y = ifft2(..., 'nonsymmetric')
Description Y = ifft2(X) returns the two-dimensional inverse discrete Fourier transform
(DFT) of X, computed with a fast Fourier transform (FFT) algorithm. The
result Y is the same size as X.
ifft2 tests X to see whether it is conjugate symmetric. If so, the computation
is faster and the output is real. An M-by-N matrix X is conjugate symmetric if
X(i,j) = conj(X(mod(M-i+1, M) + 1, mod(N-j+1, N) + 1)) for each element
of X.
Y = ifft2(X,m,n) returns the m-by-n inverse fast Fourier transform of
matrix X.
y = ifft2(..., 'symmetric') causes ifft2 to treat X as conjugate symmetric.
This option is useful when X is not exactly conjugate symmetric, merely
because of round-off error.
y = ifft2(..., 'nonsymmetric') is the same as calling ifft2(...) without
the argument 'nonsymmetric'.
For any X, ifft2(fft2(X)) equals X to within roundoff error.
Algorithm The algorithm for ifft2(X) is the same as the algorithm for fft2(X), except
for a sign change and scale factors of [m,n] = size(X). The execution time for
ifft2 depends on the length of the transform. It is fastest for powers of two. It
is almost as fast for lengths that have only small prime factors. It is typically
several times slower for lengths that are prime or which have large prime
factors.
Note You might be able to increase the speed of ifft2 using the utility
function fftw, which controls how MATLAB optimizes the algorithm used to
compute an FFT of a particular size and dimension.
ifft2
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