Special Arguments

This section describes the flag and hint arguments used by the Fourier transform functions.

The Fourier transform functions require you to specify the flag and hint arguments.

The flag argument specifies the result normalization method. The following table lists the possible values for the flag argument. Specify one and only one of the represented values in the flag argument. The A and B factors are multipliers used in the DFT computation.

Flag Arguments for Fourier Transform Functions
Value	A	B	Description
IPP_FFT_DIV_FWD_BY_N	1/N	1	Forward transform is done with the 1/N normalization.
IPP_FFT_DIV_INV_BY_N	1	1/N	Inverse transform is done with the 1/N normalization.
IPP_FFT_DIV_BY_SQRTN	1/N^1/2	1/N^1/2	Forward and inverse transform is done with the 1/ N^1/2 normalization.
IPP_FFT_NODIV_BY_ANY	1	1	Forward or inverse transform is done without the 1/ N or 1/N^1/2normalization.

The hint argument suggests using special code, faster but less accurate calculation, or more accurate but slower calculation. The following table lists values you can enter for the hint argument.

Note that the hint argument is also used for some other operations (for example, for tone generation, logarithmic addition).

Hint Arguments for Fourier Transform Functions
Value	Description
ippAlgHintNone	No suggestions. The function selects an algorithm
ippAlgHintFast	Fast algorithm is suggested for computation.
ippAlgHintAccurate	Accurate algorithm is suggested for computation.