/*
**  $Id: runningmean.c,v 1.1 1997/12/22 19:56:53 frank Exp $
**  runningmean.c 1.0	Solaris 2.6 Unix	971218	SIO/ODF	fmd
**
**  Running Mean functions
*/
#include <odflib.h>
#include <math.h>

RunningMean
RunningMeanInit(int n, double initVal)
{
	int		i;
	double		sum, *pQ;
	RunningMean	pR;

	if (n<1)
	    n		= 1;
	pR		= (RunningMean)malloc(sizeof (RunningMeanDesc)+
				n * sizeof (double));
	pR->q		= (double *)&pR[1];
	for (i=0, sum=initVal, pQ=pR->q; i<n;
	    *pQ++ = initVal, i++, sum += initVal);
	pR->sum		= sum;
	pR->last	= 0;
	pR->n		= n;
	return (pR);
}

double
RunningMeanReset(RunningMean pR, double initVal)
{
	int		i, n;
	double		sum, *pQ;
	for (i=0, n=pR->n, pQ=pR->q, sum=initVal; i<n;
	    *pQ++ = initVal, i++, sum += initVal);
	pR->sum		= sum;
	pR->last	= 0;
	return (initVal);
}

double
RunningMeanCalc(RunningMean pR, double val)
{
	double		newVal, *pQ = pR->q, sum = pR->sum;
	int		index = pR->last, n = pR->n;

	pR->sum		=
	sum		= sum-pQ[index]+val;
	pQ[index]	= val;
	newVal		= sum / n;
	pR->last	= (++index) % n;
	return (newVal);
}