KahanSummation.h

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* libscopehal                                                                                                          *
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* Copyright (c) 2012-2025 Andrew D. Zonenberg and contributors                                                         *
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#ifndef KahanSummation_h
#define KahanSummation_h
 
class KahanSummation
{
public:
    KahanSummation()
    { Reset(); }
 
    void Reset(float f = 0)
    {
        m_partialSum = f;
        m_errorTerm = 0;
    }
 
    float operator+=(float rhs)
    {
        float y = rhs - m_errorTerm;
        float t = m_partialSum + y;
        m_errorTerm = (t - m_partialSum) - y;
        m_partialSum = t;
        return m_partialSum;
    }
 
    float GetSum()
    { return m_partialSum; }
 
protected:
 
    //The working sum
    float m_partialSum;
 
    //Error term (low bits that got rounded off)
    float m_errorTerm;
};
 
#endif