qmeanvarianceaccumulator_p.h

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// Copyright (C) 2025 The Qt Company Ltd.

// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only

#ifndef QMEANVARIANCEACCUMULATOR_P_H

#define QMEANVARIANCEACCUMULATOR_P_H

//

//  W A R N I N G

//  -------------

//

// This file is not part of the Qt API.  It exists purely as an

// implementation detail.  This header file may change from version to

// version without notice, or even be removed.

//

// We mean it.

//

#include <QtTest/private/qbenchmarkmeasurement_p.h>

QT_BEGIN_NAMESPACE

namespace QTestPrivate {

class MeanAndVarianceAccumulator

    qsizetype m_count = 0;

    qreal m_mean = 0;

    qreal m_sqdiff = 0;

public:

    MeanAndVarianceAccumulator() = default;

    void update(qreal value)

        const qreal gap = value - m_mean;

        ++m_count;

        m_mean += gap / m_count;

        m_sqdiff += gap * (value - m_mean);

    qsizetype count() const { return m_count; }

    qreal mean() const { return m_mean; }

    qreal variance() const { return m_count > 1 ? m_sqdiff / (m_count - 1) : 0;  }

    qreal total() const { return m_mean * m_count; }

    void reset() { m_mean = 0; m_sqdiff = 0; m_count = 0; }

};

} // namespace QTestPrivate

QT_END_NAMESPACE

#endif // QBENCHMARKTIMEMEASURERS_P_H