Intel® Integrated Performance Primitives (Intel® IPP) Developer Guide and Reference

ID 790148
Date 10/31/2024
Public
Document Table of Contents

DFTFwd_Direct_CToC

Computes the forward discrete Fourier transform of a complex signal.

Syntax

IppStatus ippsDFTFwd_Direct_CToC_16fc(const Ipp16fc *pSrc, Ipp16fc *pDst, int length);

Include Files

ipps.h

Domain Dependencies

Flavors declared in ipps.h:

Headers: ippcore.h, ippvm.h

Libraries: ippcore.lib, ippvm.lib

Parameters

pSrc

Pointer to the input array containing complex values.

pDst

Pointer to the output array containing complex values.

length

Length of transform

Description

This function computes the forward DFT according to the transform length.

The function operating on the complex data type processes the input complex array pSrc and stores the result in pDst.

NOTE:

Data vectors for this function must be aligned to an appropriate number of bytes that is determined by the SIMD width that is supported by the customer's platform - use ippMalloc function for such alignment.

The direct form of DFT uses the static twiddle tables and therefore supports only the limited set of transform lengths. 47 DFT lengths and 11 FFT lengths: 12, 24, 36, 48, 60, 72, 96, 108, 120, 144, 180, 192, 216, 240, 288, 300, 324, 360, 384, 432, 480, 540, 576, 600, 648, 720, 768, 864, 900, 960, 972, 1080, 1152, 1200, 1296, 1440, 1500, 1536, 1620, 1920, 1944, 2160, 2400, 2700, 2916, 3000, 3240 - DFT, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096 - FFT

The forward DFT functionality can be described as follows:



where k is the index of elements in the frequency domain, n is the index of elements in the time domain, N is the input signal len, and A is a multiplier equal to 1.0 (no normalization). Also, x(n) is pSrc[n] and X(k) is pDst[k].

Product and Performance Information

Performance varies by use, configuration and other factors. Learn more at www.Intel.com/PerformanceIndex.

Notice revision #20201201

Return Values

ippStsNoErr

Indicates no error.

ippStsNullPtrErr

Indicates an error when one of the specified pointers with exception of pBuffer is NULL.

ippStsSizeErr

This length is not supported by direct function.