IFFTSHIFT

Purpose:

Unshifts a 1D or 2D FFT so the 0 frequency is the first point.

Syntax:

IFFTSHIFT(series)

series

Any series or multi-column table.

Returns:

A series or array.

Example:

W1: {1, 2, 3, 2, 1}

W2: fft(W1)

W3: fftshift(W2)

W4: ifftshift(W3)

The zero frequency (i.e. DC) value of W2 is the first point. The zero frequency of W3 is the 3rd point and appears in the middle of the resulting graph. W4 undoes the shift of W3 to return the same data as in W2.

Remarks:

IFFTSHIFT also works on 2D FFT array.

IFFTSHIFT undoes the shift produced by FFTSHIFT. For a series or array with an odd number of elements,

ifftshift(fftshift(s))

returns the original but

fftshift(fftshift(s))