/*widla determine Lya line width for radiation pressure */
#include <string.h>
#include "cddefines.h"
#include "pressure.h"
#include "touton.h"
#include "redis.h"
#include "rtescprob.h"
#include "phycon.h"
#include "widlin.h"
#include "widla.h"

double widla(
				 double tauin, 
				 double tauout, 
				 double a, 
				 /* answer will be in whatever units vth is in, since only generates
				  * optical depth dependent scale factor */
				 double vth)
{
	static int lgTonSav;
	double t, 
	  tau, 
	  therm, 
	  widla_v;

#	ifdef DEBUG_FUN
	fputs( "<+>widla()\n", debug_fp );
#	endif

	/* optical depth in outer direction is always defined for la */
	lgTonSav = touton.lgTauOutOn;
	touton.lgTauOutOn = TRUE;

	/* compute width of la with either complete or incomplete redistribution */
	if( strcmp(redis.chRedis,"INCO") == 0 || 
		 strcmp(redis.chRedis,"WIND") == 0 )
	{
		widla_v = widlin(tauin,tauout,a,vth);
	}

	else if( strcmp(redis.chRedis,"COMP") == 0 )
	{

		tau = tauout/2.;
		t = MIN2(tauin,tauout-tauin);
		t = MAX2(0.,t);

		/* max optical depth is thermalization length */
		therm = POW2(3e14/phycon.eden);
		if( tau > therm )
		{
			tau = therm;
			pressure.lgPradDen = TRUE;
		}

		/* 1st fac in () is SQRT(2*pi); sec is 2/(pi^.25) */
		widla_v = vth*(2.5066 + 1.5023*sqrt(a*tau))*(1. - escinc(t,a));
	}

	else
	{
		fprintf( ioQQQ,"widla called with insane redistribution function ==%s==\n",
			redis.chRedis );
		puts( "[Stop in widla]" );
		exit(1);
	}

	/* reset the optical depths flag */
	touton.lgTauOutOn = lgTonSav;


#	ifdef DEBUG_FUN
	fputs( " <->widla()\n", debug_fp );
#	endif
	return( widla_v );
}