#ifndef _BLASR_VARIANCE_ACCUMULATOR_IMPL_HPP_
#define _BLASR_VARIANCE_ACCUMULATOR_IMPL_HPP_

template <typename T>
VarianceAccumulator<T>::VarianceAccumulator()
{
    Reset();
}

template <typename T>
void VarianceAccumulator<T>::Reset()
{
    sumSqVal = 0;
    sumVal = 0;
    nSamples = 0;
    maxVal = minVal = 0;
}

template <typename T>
T VarianceAccumulator<T>::GetMean()
{
    return ((1.0) * sumVal) / nSamples;
}

template <typename T>
T VarianceAccumulator<T>::GetVariance()
{
    return (1.0 * sumSqVal) / nSamples - GetMean() * GetMean();
}

template <typename T>
float VarianceAccumulator<T>::GetNStdDev(T value)
{
    T variance = GetVariance();
    T mean = GetMean();
    if (variance > 0) {
        return std::fabs(value - mean) / (std::sqrt(variance));
    } else {
        return 0;
    }
}

template <typename T>
void VarianceAccumulator<T>::Append(T v)
{
    if (nSamples == 0) {
        maxVal = minVal = v;
    } else {
        if (maxVal < v) {
            maxVal = v;
        }
        if (minVal > v) {
            minVal = v;
        }
    }
    sumSqVal += v * v;
    sumVal += v;
    nSamples++;
}

#endif