LALEtaTau04.c

Go to the documentation of this file.

/*
*  Copyright (C) 2007 Duncan Brown, Jolien Creighton, B.S. Sathyaprakash
*
*  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="LALEtaTau04CV">
Author: Sathyaprakash, B. S.
$Id: LALEtaTau04.c,v 1.10 2007/06/08 14:41:49 bema Exp $
</lalVerbatim>  */

/*  <lalLaTeX>

\subsection{Module \texttt{LALEtaTau04.c}}
Given $\tau_0$ and $\tau_4$ solve for the mass ratio $\eta.$
\subsubsection*{Prototypes}
\vspace{0.1in}
\input{LALEtaTau04CP}
\idx{LALEtaTau04()}

\subsubsection*{Description}
Given $\tau_0$ and $\tau_4$ one can determine $\eta$ by solving 
\begin{equation}
-\eta^{4/5} \tau_4 + A_4 \left ( \frac {\tau_0}{A_0} \right )^{1/5}  
\left (1 + B_4\eta + C_4 \eta^2 \right )  = 0,
\end{equation}
where $A_0 = 5/[256 (\pi f_{s} )^{8/3}],$ 
$A_4 = 5 \times 3058673/ [128 \times 1016064  (\pi f_s)^{4/3}],$
$B_4 = 5429 \times 1016064 /(1008 \times 3058673),$ and $C_4 = 617 \times
1016064/(144 \times 3058673).$
This function returns the LHS of the above
equation in \texttt{x} for a given \texttt{eta}.


\subsubsection*{Algorithm}
None.

\subsubsection*{Uses}
None.

\subsubsection*{Notes}
The {\tt void pointer} {\tt *p} should point to a {\tt struct}
of type {\tt EtaTau04In}\\[10pt]
{\tt 
void *p;\\
EtaTau04In q;\\[5pt]
$\ldots$\\
p = (void *) \&q;\\
}
</lalLaTeX> */

#include <lal/LALInspiral.h>

NRCSID (LALETATAU04C, "$Id: LALEtaTau04.c,v 1.10 2007/06/08 14:41:49 bema Exp $");
/*  <lalVerbatim file="LALEtaTau04CP"> */
void 
LALEtaTau04(
   LALStatus *status, 
   REAL8     *x, 
   REAL8     eta, 
   void      *p
   ) 
{ /* </lalVerbatim> */
   EtaTau04In *q;
   INITSTATUS(status, "LALEtaTau04", LALETATAU04C);
   ATTATCHSTATUSPTR(status);
   ASSERT (p,  status, LALINSPIRALH_ENULL, LALINSPIRALH_MSGENULL);
   ASSERT(eta > 0, status, LALINSPIRALH_ESIZE, LALINSPIRALH_MSGESIZE);

   q = (EtaTau04In *) p;
   *x = -q->t4 + q->A4/pow(eta,0.8) * (1. + q->B4*eta + q->C4*eta*eta);
   DETATCHSTATUSPTR(status);
   RETURN(status);
}

---