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ifftshift

Inverse zero-frequency shift

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Syntax

X = ifftshift(Y)
X = ifftshift(Y,dim)

Description

X = ifftshift(Y) rearranges a zero-frequency-shifted Fourier transform Y back to the original transform output. In other words, ifftshift undoes the result of fftshift.

  • If Y is a vector, then ifftshift swaps the left and right halves of Y.

  • If Y is a matrix, then ifftshift swaps the first quadrant of Y with the third, and the second quadrant with the fourth.

  • If Y is a multidimensional array, then ifftshift swaps half-spaces of Y along each dimension.

example

X = ifftshift(Y,dim) operates along the dimension dim of Y. For example, if Y is a matrix whose rows represent multiple 1-D transforms, then ifftshift(Y,2) swaps the halves of each row of Y.

example

Examples

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Open Live Script

You can use the fftshift and ifftshift functions to swap left and right halves of a vector.

Create a vector containing an odd number of elements, and swap the left and right sides of the vector using the fftshift function.

V = [1 2 3 4 5 6 7];
X = fftshift(V)
X = 1×7

     5     6     7     1     2     3     4

Use the ifftshift function to swap the left and right sides of X. The result is the same as the original vector V.

Y = ifftshift(X)
Y = 1×7

     1     2     3     4     5     6     7

Calling the fftshift function twice does not necessarily reconstruct the original input.

fftshift(fftshift(V))
ans = 1×7

     2     3     4     5     6     7     1
Open Live Script

Rearrange the rows of a matrix to shift the nonnegative elements to the left.

Y = [-2 -1 0 1 2; 
    -10 -5 0 5 10];
X = ifftshift(Y,2)
X = 2×5

     0     1     2    -2    -1
     0     5    10   -10    -5

Input Arguments

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Input array, specified as a vector, a matrix, or a multidimensional array.

Data Types: double | single | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | logical
Complex Number Support: Yes

Dimension to operate along, specified as a positive integer scalar. If no value is specified, then ifftshift swaps along all dimensions.

  • Consider an input matrix Yc. The operation ifftshift(Yc,1) swaps halves of each column of Yc.

    ifft(Yc,1) column-wise operation

  • Consider an input matrix Yr. The operation ifftshift(Yr,2) swaps halves of each row of Yr.

    ifft(Yr,2) row-wise operation

Data Types: double | single | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | logical

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.

GPU Code Generation
Generate CUDA® code for NVIDIA® GPUs using GPU Coder™.

Version History

Introduced before R2006a

See Also

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