CrossSpectrum

Advanced Analysis Library Only

AnalysisLibErrType CrossSpectrum (double xArray[], double yArray[], int numberOfElements, double realSxy[], double imaginarySxy[]);

Purpose

Calculates the double-sided cross power spectrum, Sxy, of the input sequences X and Y according to the following formula:

where FFT*[X] is the complex conjugate of FFT[X] and n is the number of points in the arrays.

The input sequences are copied to internal buffers and zero-padded to numberOfElements samples before the FFTs are computed. The output arrays are the real and imaginary parts of the cross spectrum CrossSpectrum.

Parameters

Input
Name Type Description
xArray double-precision array Time-domain signal X.
yArray double-precision array Time-domain signal Y.
numberOfElements integer Number of elements in the input arrays.
Output
Name Type Description
realSxy double-precision array Real part of the double-sided cross power spectrum between signals X and Y. The size of this array must be at least numberOfElements.
imaginarySxy double-precision array Imaginary part of the double-sided cross power spectrum between signals X and Y. The size of this array must be at least numberOfElements.

Return Value

Name Type Description
status AnalysisLibErrType A value that specifies the type of error that occurred. Refer to analysis.h for definitions of these constants.