/// <summary>
/// Returns a matrix whose columns consist of autocorrelations of freq bin samples.
/// The columns are non-overlapping.
/// </summary>
public static double[,] GetXcorrByTimeMatrix(double[] signal, int sampleLength)
{
// NormaliseMatrixValues freq bin values to z-score. This is required else get spurious results
signal = DataTools.Vector2Zscores(signal);
int sampleCount = signal.Length / sampleLength;
double[,] xCorrelationsByTime = new double[sampleLength, sampleCount];
for (int s = 0; s < sampleCount; s++)
{
int start = s * sampleLength;
double[] subArray = DataTools.Subarray(signal, start, sampleLength);
double[] autocor = AutoAndCrossCorrelation.AutoCorrelationOldJavaVersion(subArray);
//DataTools.writeBarGraph(autocor);
MatrixTools.SetColumn(xCorrelationsByTime, s, autocor);
}
return(xCorrelationsByTime);
}
/// <summary>
/// Returns a matrix whose columns consist of autocorrelations of freq bin samples.
/// The columns are non-overlapping.
/// </summary>
/// <param name="signal">an array corresponding to one frequency bin.</param>
/// <param name="sampleLength">the length of a sample or patch (non-overllapping) for which xcerrelation is obtained.</param>
public static double[,] GetXcorrByTimeMatrix(double[] signal, int sampleLength)
{
// NormaliseMatrixValues freq bin values to z-score. This is required else get spurious results
signal = DataTools.Vector2Zscores(signal);
// get number of complete non-overlapping samples or patches
var sampleCount = signal.Length / sampleLength;
var xCorrelationsByTime = new double[sampleLength, sampleCount];
for (var s = 0; s < sampleCount; s++)
{
var start = s * sampleLength;
var subArray = DataTools.Subarray(signal, start, sampleLength);
// do xcorr which returns an array same length as the sample or patch.
var autocor = AutoAndCrossCorrelation.AutoCorrelationOldJavaVersion(subArray);
//DataTools.writeBarGraph(autocor);
MatrixTools.SetColumn(xCorrelationsByTime, s, autocor);
}
// return a matrix of [xCorrLength, sampleLength]
return(xCorrelationsByTime);
}
