/*MakeDeriv derive numerical derivative of heating minus cooling */
#include <string.h>
#include "cddefines.h"
#define	NSTMAX	50
#include "makederiv.h"

void MakeDeriv(char *job, 
  double hmc, 
  double te, 
  float *DerivNumer)
{
	long int i;

	static long int nstore;
	double dTe;

	static double TeSave[NSTMAX], 
	  hmcSave[NSTMAX];

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

	if( strcmp(job,"zero") == 0 )
	{
		nstore = 0;
	}
	else if( strcmp(job,"incr") == 0 )
	{
		nstore += 1;
		if( nstore > NSTMAX )
		{
			fprintf( ioQQQ, " too many stores for MakeDeriv\n" );
			nstore = NSTMAX;
		}
		hmcSave[nstore-1] = hmc;
		TeSave[nstore-1] = te;
		if( nstore > 1 )
		{
			*DerivNumer = 0.;
			for( i=0; i < (nstore - 1); i++ )
			{
				dTe = TeSave[i] - TeSave[i+1];
				if( dTe != 0. )
				{
					*DerivNumer += (float)((hmcSave[i] - hmcSave[i+1])/dTe);
				}
			}
			*DerivNumer /= nstore - 1;
		}

		else
		{
			*DerivNumer = 0.;
		}
	}
	else
	{
		fprintf( ioQQQ, " MakeDeriv called with insane job=%4.4s\n", 
		  job );
		puts( "[Stop in makederiv]" );
		exit(1);
	}

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