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vDSP_fft_zrip

Computes a forward or inverse in-place, single-precision real FFT.

Declaration

void vDSP_fft_zrip(FFTSetup __Setup, const DSPSplitComplex *__C, vDSP_Stride __IC, vDSP_Length __Log2N, FFTDirection __Direction);

Parameters

  • __Setup:

    The FFT setup structure for this transform. The setup’s structure Log2N must be greater than or equal to this function’s Log2N.

  • __C:

    A pointer to the input-output data.

  • __IC:

    The stride between the elements in C, set to 1 for best performance.

  • __Log2N:

    The base 2 exponent of the number of elements to process. For example, to process 1024 elements, specify 10 for parameter Log2N.

  • __Direction:

    A flag that specifies the transform direction. Pass Kfftdirection_forward to transform from the time domain to the frequency domain. Pass Kfftdirection_inverse to transform from the frequency domain to the time domain.

Discussion

Forward transforms read real input and write packed complex output. Inverse transforms read packed complex input and write real output. As a result of packing the frequency-domain data, time-domain data and its equivalent frequency-domain data have the same storage requirements. You can find more details on the packing format in Data Packing for Real FFTs in vDSP Programming Guide.

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where F is Direction, C is C, and N is two raised to the power of Log2N.

See also functions vDSP_create_fftsetup and vDSP_destroy_fftsetup.