The functions described in this section compute a single or a number of the discrete Fourier transforms for a given frequency. Note that the DFT exists only for the following normalized frequencies: 0, 1/

N

, 2/

N,

... (

N

-1)/

N

, where

N

is the number of time domain samples. Therefore you must select the frequency value from the above set.

These Intel IPP functions use a Goertzel algorithm [Mit98] and are more efficient when a small number of DFT values is needed.

Some of the functions compute two values, not one. The applications computing several values, for example the dual-tone multi frequency signal detection, work faster with such functions.