Function

vDSP_fft_zrip

Computes an in-place single-precision real discrete Fourier transform, either from the time domain to the frequency domain (forward) or from the frequency domain to the time domain (inverse).

Declaration

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

Parameters

__Setup

Points to a structure initialized by a prior call to the FFT setup data function, vDSP_create_fftsetup. The value supplied as parameter Log2n of the setup function Log2N of this transform function.

__C

Complex input/output vector.

__IC

Stride between elements in C. The value of IC should be 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 forward/inverse directional flag, which must specify kFFTDirection_Forward (+1) or kFFTDirection_Inverse (-1).

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.

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.