/*
This is for multi-channel "sounds" like EEG signals.
The cross-correlation between channel i and channel j is defined as
sum(k=1..nsamples, (z[i][k] - mean[i])(z[j][k + tau] - mean[j]))*samplingTime
*/
autoCrossCorrelationTable Sound_to_CrossCorrelationTable (Sound me, double startTime, double endTime, double lagStep) {
try {
if (endTime <= startTime) {
startTime = my xmin;
endTime = my xmax;
}
long lag = (long) floor (lagStep / my dx); // ppgb: voor al dit soort dingen geldt: waarom afronden naar beneden?
long i1 = Sampled_xToNearestIndex (me, startTime);
if (i1 < 1) {
i1 = 1;
}
long i2 = Sampled_xToNearestIndex (me, endTime);
if (i2 > my nx) {
i2 = my nx;
}
i2 -= lag;
long nsamples = i2 - i1 + 1;
if (nsamples <= my ny) {
Melder_throw (U"Not enough samples, choose a longer interval.");
}
autoCrossCorrelationTable thee = CrossCorrelationTable_create (my ny);
NUMcrossCorrelate_rows (my z, my ny, i1, i2, lag, thy data, thy centroid, my dx);
thy numberOfObservations = nsamples;
return thee;
} catch (MelderError) {
Melder_throw (me, U": CrossCorrelationTable not created.");
}
}
/*
This is for multi-channel "sounds" like EEG signals.
The cross-correlation between channel i and channel j is defined as
sum(k=1..nsamples, (z[i][k] - mean[i])(z[j][k + tau] - mean[j]))*samplingTime
*/
CrossCorrelationTable Sound_to_CrossCorrelationTable (Sound me, double startTime, double endTime, double lagTime) {
try {
if (endTime <= startTime) {
startTime = my xmin;
endTime = my xmax;
}
long lag = lagTime / my dx;
long i1 = Sampled_xToNearestIndex (me, startTime);
if (i1 < 1) {
i1 = 1;
}
long i2 = Sampled_xToNearestIndex (me, endTime);
if (i2 > my nx) {
i2 = my nx;
}
i2 -= lag;
long nsamples = i2 - i1 + 1;
if (nsamples <= my ny) {
Melder_throw ("Not enough samples, choose a longer interval.");
}
autoCrossCorrelationTable thee = CrossCorrelationTable_create (my ny);
NUMcrossCorrelate_rows (my z, my ny, i1, i2, lag, thy data, thy centroid, my dx);
thy numberOfObservations = nsamples;
return thee.transfer();
} catch (MelderError) {
Melder_throw (me, ": CrossCorrelationTable not created.");
}
}
/* Calculate the CrossCorrelationTable between the channels of two multichannel sounds irrespective of the domains.
* Both sounds are treated as if their domain runs from 0 to duration.
* Outside the chosen interval the sounds are assumed to be zero
*/
autoCrossCorrelationTable Sounds_to_CrossCorrelationTable_combined (Sound me, Sound thee, double relativeStartTime, double relativeEndTime, double lagStep) {
try {
if (my dx != thy dx) {
Melder_throw (U"Sampling frequencies must be equal.");
}
if (relativeEndTime <= relativeStartTime) {
relativeStartTime = my xmin;
relativeEndTime = my xmax;
}
long ndelta = (long) floor (lagStep / my dx), nchannels = my ny + thy ny;
long i1 = Sampled_xToNearestIndex (me, relativeStartTime);
if (i1 < 1) {
i1 = 1;
}
long i2 = Sampled_xToNearestIndex (me, relativeEndTime);
if (i2 > my nx) {
i2 = my nx;
}
i2 -= ndelta;
long nsamples = i2 - i1 + 1;
if (nsamples <= nchannels) {
Melder_throw (U"Not enough samples");
}
autoCrossCorrelationTable him = CrossCorrelationTable_create (nchannels);
autoNUMvector<double *> data (1, nchannels);
for (long i = 1; i <= my ny; i++) {
data[i] = my z[i];
}
for (long i = 1; i <= thy ny; i++) {
data[i + my ny] = thy z[i];
}
NUMcrossCorrelate_rows (data.peek(), nchannels, i1, i2, ndelta, his data, his centroid, my dx);
his numberOfObservations = nsamples;
return him;
} catch (MelderError) {
Melder_throw (me, U": CrossCorrelationTable not created.");
}
}
