normal_distribution.h

// Description: Normal distribution

#ifndef PASTELSYS_NORMAL_DISTRIBUTION_H
#define PASTELSYS_NORMAL_DISTRIBUTION_H

#include "pastel/sys/real/real_concept.h"
#include "pastel/math/matrix.h"

namespace Pastel
{

    template <typename Real>
    class Normal_Distribution
    {
    public:
        using Point = ColMatrix<Real>;

        explicit Normal_Distribution(integer n = 1)
        : mean_(ColMatrix<Real>::Zero(n))
        , scale_(ColMatrix<Real>::One(n))
        , rotation_(Matrix<Real>::Identity(n, n))
        , detCovariance_(1)
        {
        }

        Normal_Distribution(const Normal_Distribution&) = default;
        Normal_Distribution(Normal_Distribution&&) = default;
        Normal_Distribution& operator=(const Normal_Distribution&) = default;
        Normal_Distribution& operator=(Normal_Distribution&&) = default;

        Normal_Distribution(
            ColMatrix<Real> mean,
            ColMatrix<Real> scale,
            Matrix<Real> rotation)
        : mean_(std::move(mean))
        , scale_(std::move(scale))
        , rotation_(std::move(rotation))
        , detCovariance_(0)
        {
            ENSURE_OP(mean.size(), ==, rotation.rows());
            ENSURE_OP(mean.size(), ==, rotation.cols());
            detCovariance_ = scale_.prod();
        }

        integer n() const
        {
            return mean_.size();
        }

        const ColMatrix<Real>& mean() const {
            return mean_;
        }

        const ColMatrix<Real>& scale() const {
            return scale_;
        }

        const Matrix<Real>& rotation() const {
            return rotation_;
        }

        Real detCovariance() const {
            return detCovariance_;
        }

    private:
        ColMatrix<Real> mean_;
        ColMatrix<Real> scale_;
        Matrix<Real> rotation_;
        Real detCovariance_;
    };

}

#endif