Goertz
Goertz
Computes the discrete Fourier transform for a given frequency for a single signal.
Syntax
IppStatus ippsGoertz_32f(const Ipp32f*
pSrc
, int
len
, Ipp32fc*
pVal
, Ipp32f
rFreq
);
IppStatus ippsGoertz_64f(const Ipp64f*
pSrc
, int
len
, Ipp64fc*
pVal
, Ipp64f
rFreq
);
IppStatus ippsGoertz_32fc(const Ipp32fc*
pSrc
, int
len
, Ipp32fc*
pVal
, Ipp32f
rFreq
);
IppStatus ippsGoertz_64fc(const Ipp64fc*
pSrc
, int
len
, Ipp64fc*
pVal
, Ipp64f
rFreq
);
IppStatus ippsGoertz_16s_Sfs(const Ipp16s*
pSrc
, int
len
, Ipp16sc*
pVal
, Ipp32f
rFreq
, int
scaleFactor
);
IppStatus ippsGoertz_16sc_Sfs(const Ipp16sc*
pSrc
, int
len
, Ipp16sc*
pVal
, Ipp32f
rFreq
, int
scaleFactor
);
Include Files
ipps.h
Domain Dependencies
Headers:
ippcore.h
,
ippvm.h
Libraries:
ippcore.lib
,
ippvm.lib
Parameters
- pSrc
- Pointer to the input data vector.
- len
- Number of elements in the vector.
- pVal
- Pointer to the output DFT value.
- rFreq
- Single relative frequency value [0, 1.0).
- scaleFactor
- Scale factor, refer to Integer Scaling.
Description
This function computes a DFT for an input
len
-length vector pSrc
for a given frequency rFreq
, and stores the result in pVal
.ippsGoertzQ15
. This function operates with relative frequency in Q15 format. Data in Q15 format are converted to the corresponding float data type that lay in the range [0, 1.0).The functionality of the Goertzel algorithm can be described as follows:
where
k
/N
is the normalized rFreq
value for which the DFT is computed.Return Values
- ippStsNoErr
- Indicates no error.
- ippStsNullPtrErr
- Indicates an error when one of the specified pointers isNULL.
- ippStsRelFreqErr
- Indicates an error whenrFreqis out of range.
- ippStsSizeErr
- Indicates an error whenlenis less than or equal to 0.
Example
The example below illustrates the use of Goertzel functions for selecting the magnitudes of a given frequency when computing DFTs.
IppStatus goertzel( void ) { #undef LEN #define LEN 100 IppStatus status; Ipp32fc *x = ippsMalloc_32fc( LEN ), y; int n; ///generate a signal of 60 Hz freq that /// is sampled with 400 Hz freq for( n=0; n<LEN; ++n) { x[n].re =(Ipp32f)sin(IPP_2PI * n * 60 / 400); x[n].im = 0; } status = ippsGoertz_32fc( x, LEN, &y, 60.0f / 400 ); printf_32fc("goertz =", &y, 1, status ); ippsFree( x ); return status; }
Output:
goertz = {0.000090,-50.000008} Matlab* Analog >> N=100;F=60/400;n=0:N-1;x=sin(2*pi*n*F);y=fft(x);n=N*F;y(n+1)