#include <math.h>
#include "onlinemean.h"

void OnlineMean_Init(OnlineMean_t *oMean) {
	OnlineMean_Reset(oMean);
}

void OnlineMean_Update(OnlineMean_t *oMean, float newValue) {
	oMean->count++;
	if (oMean->count > 1) {
		float delta = newValue - oMean->mean;
		oMean->mean += delta / oMean->count;
		oMean->varsum += delta * (newValue - oMean->mean);
	} else {
		oMean->mean = newValue;
	}
}

float OnlineMean_GetMean(OnlineMean_t *oMean) {
	return oMean->mean;
}

float OnlineMean_GetStd(OnlineMean_t *oMean) {
	if (oMean->count == 0)
		return 0;
#if UNBIASED_ESTIMATOR
	return sqrt(oMean->varsum / (oMean->count - 1));
#else
	return sqrt(oMean->varsum / oMean->count);
#endif  /* UNBIASED_ESTIMATOR */
}

void OnlineMean_Reset(OnlineMean_t *oMean) {
	oMean->count = 0;
	oMean->mean = 0.f;
	oMean->varsum = 0.f;
}