/*--------------------------------------------------
* calculate the difference of two SFT-vectors
*--------------------------------------------------*/
SFTVector *
subtractSFTVectors ( const SFTVector *sftvect1, const SFTVector *sftvect2 )
{
XLAL_CHECK_NULL ( (sftvect1 != NULL) && (sftvect2 != NULL), XLAL_EINVAL );
XLAL_CHECK_NULL ( sftvect1->length == sftvect2->length, XLAL_EINVAL );
UINT4 numSFTs = sftvect1->length;
UINT4 numBins = sftvect1->data[0].data->length;
SFTVector *vect;
XLAL_CHECK_NULL ( (vect = XLALCreateSFTVector ( numSFTs, numBins )) != NULL, XLAL_EFUNC );
for ( UINT4 alpha = 0; alpha < numSFTs; alpha ++ )
{
for ( UINT4 j=0; j < numBins; j++ )
{
vect->data[alpha].data->data[j] = sftvect1->data[alpha].data->data[j] - sftvect2->data[alpha].data->data[j];
}
} /* for alpha < numSFTs */
return vect;
} /* subtractSFTVectors() */
///
/// Make SFTs from given REAL8TimeSeries at given timestamps, potentially applying a time-domain window on each timestretch first
///
SFTVector *
XLALMakeSFTsFromREAL8TimeSeries ( const REAL8TimeSeries *timeseries, //!< input time-series
const LIGOTimeGPSVector *timestamps, //!< timestamps to produce SFTs for (can be NULL), if given must all lies within timeseries' time-span
const char *windowType, //!< optional time-domain window function to apply before FFTing
REAL8 windowBeta //!< window parameter, if any
)
{
XLAL_CHECK_NULL ( timeseries != NULL, XLAL_EINVAL, "Invalid NULL input 'timeseries'\n");
XLAL_CHECK_NULL ( timestamps != NULL, XLAL_EINVAL, "Invalid NULL input 'timestamps'\n");
REAL8 dt = timeseries->deltaT; // timeseries timestep */
REAL8 Tsft = timestamps->deltaT;
REAL8 df = 1.0 / Tsft; // SFT frequency spacing
// make sure that number of timesamples/SFT is an integer (up to possible rounding error 'eps')
REAL8 timestepsSFT0 = Tsft / dt;
UINT4 timestepsSFT = lround ( timestepsSFT0 );
XLAL_CHECK_NULL ( fabs ( timestepsSFT0 - timestepsSFT ) / timestepsSFT0 < eps, XLAL_ETOL,
"Inconsistent sampling-step (dt=%g) and Tsft=%g: must be integer multiple Tsft/dt = %g >= %g\n",
dt, Tsft, timestepsSFT0, eps );
// prepare window function if requested
REAL8Window *window = NULL;
if ( windowType != NULL ) {
XLAL_CHECK_NULL ( (window = XLALCreateNamedREAL8Window ( windowType, windowBeta, timestepsSFT )) != NULL, XLAL_EFUNC );
}
// ---------- Prepare FFT ----------
REAL8Vector *timeStretchCopy; // input array of length N
XLAL_CHECK_NULL ( (timeStretchCopy = XLALCreateREAL8Vector ( timestepsSFT )) != NULL, XLAL_EFUNC, "XLALCreateREAL4Vector(%d) failed.\n", timestepsSFT );
UINT4 numSFTBins = timestepsSFT / 2 + 1; // number of positive frequency-bins + 'DC' to be stored in SFT
fftw_complex *fftOut; // output array of length N/2 + 1
XLAL_CHECK_NULL ( (fftOut = fftw_malloc ( numSFTBins * sizeof(fftOut[0]) )) != NULL, XLAL_ENOMEM, "fftw_malloc(%d*sizeof(complex)) failed\n", numSFTBins );
fftw_plan fftplan; // FFTW plan
LAL_FFTW_WISDOM_LOCK;
XLAL_CHECK_NULL ( (fftplan = fftw_plan_dft_r2c_1d ( timestepsSFT, timeStretchCopy->data, fftOut, FFTW_ESTIMATE)) != NULL, XLAL_EFUNC ); // FIXME: or try FFTW_MEASURE
LAL_FFTW_WISDOM_UNLOCK;
LIGOTimeGPS tStart = timeseries->epoch;
// get last possible start-time for an SFT
REAL8 duration = round ( timeseries->data->length * dt ); // rounded to seconds
LIGOTimeGPS tLast = tStart;
XLALGPSAdd( &tLast, duration - Tsft );
// check that all timestamps lie within [tStart, tLast]
for ( UINT4 i = 0; i < timestamps->length; i ++ )
{
char buf1[256], buf2[256];
XLAL_CHECK_NULL ( XLALGPSDiff ( &tStart, &(timestamps->data[i]) ) <= 0, XLAL_EDOM, "Timestamp i=%d: %s before start-time %s\n",
i, XLALGPSToStr ( buf1, &(timestamps->data[i]) ), XLALGPSToStr ( buf2, &tStart ) );
XLAL_CHECK_NULL ( XLALGPSDiff ( &tLast, &(timestamps->data[i]) ) >=0, XLAL_EDOM, "Timestamp i=%d: %s after last start-time %s\n",
i, XLALGPSToStr ( buf1, &(timestamps->data[i]) ), XLALGPSToStr ( buf2, &tLast ) );
}
UINT4 numSFTs = timestamps->length;
// prepare output SFT-vector
SFTVector *sftvect;
XLAL_CHECK_NULL ( (sftvect = XLALCreateSFTVector ( numSFTs, numSFTBins )) != NULL, XLAL_EFUNC,
"XLALCreateSFTVector(numSFTs=%d, numBins=%d) failed.\n", numSFTs, numSFTBins );
// main loop: apply FFT to the requested time-stretches and store in output SFTs
for ( UINT4 iSFT = 0; iSFT < numSFTs; iSFT++ )
{
SFTtype *thisSFT = &(sftvect->data[iSFT]); // point to current SFT-slot to store output in
// find the start-bin for this SFT in the time-series
REAL8 offset = XLALGPSDiff ( &(timestamps->data[iSFT]), &tStart );
INT4 offsetBins = lround ( offset / dt );
// copy timeseries-data for that SFT into local buffer
memcpy ( timeStretchCopy->data, timeseries->data->data + offsetBins, timeStretchCopy->length * sizeof(timeStretchCopy->data[0]) );
// window the current time series stretch if required
REAL8 sigma_window = 1;
if ( window != NULL )
{
sigma_window = sqrt ( window->sumofsquares / window->data->length );
for( UINT4 iBin = 0; iBin < timeStretchCopy->length; iBin++ ) {
timeStretchCopy->data[iBin] *= window->data->data[iBin];
}
} // if window
// FFT this time-stretch
fftw_execute ( fftplan );
// fill the header of the i'th output SFT */
strcpy ( thisSFT->name, timeseries->name );
thisSFT->epoch = timestamps->data[iSFT];
thisSFT->f0 = timeseries->f0; // SFT starts at heterodyning frequency
thisSFT->deltaF = df;
// normalize DFT-data to conform to v2 specification ==> multiply DFT by (dt/sigma{window})
// the SFT normalization in case of windowing follows the conventions detailed in the SFTv2 specification,
// namely LIGO-T040164, and in particular Eqs.(3),(4) and (6) in T010095-00.pdf
// https://dcc.ligo.org/cgi-bin/private/DocDB/ShowDocument?.submit=Number&docid=T010095
// https://dcc.ligo.org/DocDB/0026/T010095/000/T010095-00.pdf
REAL8 norm = dt / sigma_window;
for ( UINT4 k = 0; k < numSFTBins ; k ++ ) {
thisSFT->data->data[k] = (COMPLEX8) ( norm * fftOut[k] );
}
// correct heterodyning-phase, IF NECESSARY: ie if (fHet * tStart) is not an integer, such that phase-corr = multiple of 2pi
if ( ( (INT4)timeseries->f0 != timeseries->f0 ) || (timeseries->epoch.gpsNanoSeconds != 0) || (thisSFT->epoch.gpsNanoSeconds != 0) ) {
XLAL_CHECK_NULL ( XLALcorrect_phase ( thisSFT, timeseries->epoch) == XLAL_SUCCESS, XLAL_EFUNC );
}
} // for iSFT < numSFTs
// free memory
fftw_free ( fftOut );
LAL_FFTW_WISDOM_LOCK;
fftw_destroy_plan ( fftplan );
LAL_FFTW_WISDOM_UNLOCK;
XLALDestroyREAL8Vector ( timeStretchCopy );
XLALDestroyREAL8Window ( window );
return sftvect;
} // XLALMakeSFTsFromREAL8TimeSeries()
