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回复 沙发 jww100 的帖子
y = ifft(X) returns the inverse discrete Fourier transform (DFT) of vector X, computed with a fast Fourier transform (FFT) algorithm. If X is a matrix, ifft returns the inverse DFT of each column of the matrix.
ifft tests X to see whether vectors in X along the active dimension are conjugate symmetric. If so, the computation is faster and the output is real. An N-element vector x is conjugate symmetric if x(i) = conj(x(mod(N-i+1,N)+1)) for each element of x.
If X is a multidimensional array, ifft operates on the first non-singleton dimension.
y = ifft(X,n) returns the n-point inverse DFT of vector X.
y = ifft(X,[],dim) and y = ifft(X,n,dim) return the inverse DFT of X across the dimension dim.
y = ifft(..., 'symmetric') causes ifft to treat X as conjugate symmetric along the active dimension. This option is useful when X is not exactly conjugate symmetric, merely because of round-off error.
y = ifft(..., 'nonsymmetric') is the same as calling ifft(...) without the argument 'nonsymmetric'.
For any X, ifft(fft(X)) equals X to within roundoff error.
貌似说的很清楚 |
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发表于 2008-9-16 08:55
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