LALInspiralWaveLength.c

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/*
*  Copyright (C) 2007 David Churches, Duncan Brown, Jolien Creighton, B.S. Sathyaprakash, Thomas Cokelaer
*
*  This program is free software; you can redistribute it and/or modify
*  it under the terms of the GNU General Public License as published by
*  the Free Software Foundation; either version 2 of the License, or
*  (at your option) any later version.
*
*  This program is distributed in the hope that it will be useful,
*  but WITHOUT ANY WARRANTY; without even the implied warranty of
*  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
*  GNU General Public License for more details.
*
*  You should have received a copy of the GNU General Public License
*  along with with program; see the file COPYING. If not, write to the
*  Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
*  MA  02111-1307  USA
*/

/*  <lalVerbatim file="LALInspiralWaveLengthCV">
Author: Sathyaprakash, B. S.
$Id: LALInspiralWaveLength.c,v 1.16 2007/06/08 14:41:49 bema Exp $
</lalVerbatim>  */

/*  <lalLaTeX>

\subsection{Module \texttt{LALInspiralWaveLength.c}}

Module to calculate the number of data points (to the nearest power of 2)
needed to store a waveform.

\subsubsection*{Prototypes}
\vspace{0.1in}
\input{LALInspiralWaveLengthCP}
\idx{LALInspiralWaveLength()}
\begin{itemize}
\item {\tt length:} output, number of bins to the nearest power of 2
greater than the minimum length required to store a wave of parameters as in {\tt params}.
\item {\tt params:} input, parameters of the binary system. 
\end{itemize}

\subsubsection*{Description}


This module first calls {\tt LALInspiralChooseModel,} which gives the length of the 
waveform in seconds. That function returns an estimated waveform length. However, the 
length might not be appropriate in some extreme cases (large masses and large lower 
cut-off frequency). It is especially true in the EOB case. Therefore, we introduce 
two constants namely LALINSPIRAL\_LENGTHOVERESTIMATION (in percentage) which 
overestimate the length of the waveform and LALINSPIRAL\_MINIMALWAVELENGTH which is
the minimal waveform length in seconds. Multiplying this by the sampling rate 
{\tt params.tSampling} gives the minimum number of samples needed to hold the waveform. 
To this are added the number of bins of leading and trailing zeroes requested by the user in 
{\tt params.nStartPad} and {\tt params.nEndPad.} The resulting number is rounded to
an upward power of 2 and returned in {\tt length}. 

\subsubsection*{Algorithm}


\subsubsection*{Uses}
This function calls:\\
\texttt{
LALInspiralSetup\\
LALInspiralChooseModel
}

\vfill{\footnotesize\input{LALInspiralWaveLengthCV}}

</lalLaTeX>  */

#include <lal/LALInspiral.h>
#include <lal/LALStdlib.h>

#define  LALINSPIRAL_LENGTHOVERESTIMATION  0.1       /* 10 % */
#define  LALINSPIRAL_MINIMALWAVELENGTH     0.03125   /* 64 bins with a 2048Hz sampling*/


NRCSID (LALINSPIRALWAVELENGTHC, "$Id: LALInspiralWaveLength.c,v 1.16 2007/06/08 14:41:49 bema Exp $");

/*  <lalVerbatim file="LALInspiralWaveLengthCP"> */
void 
LALInspiralWaveLength(
   LALStatus        *status, 
   UINT4            *length,
   InspiralTemplate  params
   ) 
{ /* </lalVerbatim>  */

   INT4 ndx;
   REAL8 x;
   CHAR message[256];
   expnCoeffs ak;
   expnFunc func;

   INITSTATUS (status, "LALInspiralWaveLength", LALINSPIRALWAVELENGTHC);
   ATTATCHSTATUSPTR(status);

   ASSERT (params.nStartPad >= 0, status, LALINSPIRALH_ESIZE, LALINSPIRALH_MSGESIZE);
   ASSERT (params.nEndPad >= 0, status, LALINSPIRALH_ESIZE, LALINSPIRALH_MSGESIZE);
   ASSERT (params.tSampling > 0, status, LALINSPIRALH_ESIZE, LALINSPIRALH_MSGESIZE);
   ASSERT (&params, status, LALINSPIRALH_ENULL, LALINSPIRALH_MSGENULL);

   LALInspiralSetup (status->statusPtr, &ak, &params);
   CHECKSTATUSPTR(status);
   
   LALInspiralChooseModel(status->statusPtr, &func, &ak, &params);
   /* not checkstatus before but we check if everything is fine, 
      then we return the length otherwise length is zero*/
   if (status->statusPtr->statusCode == 0){
           /*we add a minimal value and 10 % of overestimation */
           x    = (1.+ LALINSPIRAL_LENGTHOVERESTIMATION) * (ak.tn + LALINSPIRAL_MINIMALWAVELENGTH ) * params.tSampling 
             + params.nStartPad + params.nEndPad;
           ndx  = ceil(log10(x)/log10(2.));
           *length = pow(2, ndx);
     
        DETATCHSTATUSPTR(status);
        RETURN(status);
   }
   else { 
        sprintf(message,
                "size is zero for the following waveform: totalMass = %f, fLower = %f, approximant = %d @ %fPN"
               , params.mass1 + params.mass2, params.fLower, params.approximant, params.order/2.);
        LALWarning(status, message);
        *length = 0;
       
       DETATCHSTATUSPTR(status);
       RETURN(status);
     }
}

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