/*grngam compute grains photoionization rates */
#include "cddefines.h"
#include "rfield.h"
#include "grainvar.h"
#include "grngam.h"

double grngam(
				  /* pointer to grain type */
				  long int nd)
{
	long int i;
	float grngam_v, 
	  partin, 
	  partot, 
	  suminc, 
	  sumots;

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

	sumots = 0.;
	suminc = 0.;
	grngam_v = 0.;

	for( i=GrainVar.ipDustPot[nd]-1; i < rfield.nflux; i++ )
	{
		partot = MAX2(0.f,1.f-GrainVar.dstpot[nd]/GrainVar.DustPhotoE[nd][i]);

		GrainVar.yhat[nd][i] = GrainVar.yn[nd][i]*MIN2(1.f,partot);

		partot = rfield.SummedDif[i]*GrainVar.yhat[nd][i]*GrainVar.dqabs[nd][i];

		sumots += partot;
		partin = rfield.flux[i]*GrainVar.yhat[nd][i]*GrainVar.dqabs[nd][i];
		suminc += partin;

	}

	grngam_v = sumots + suminc;


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