matrix.hpp

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/* ----------------------------------------------------------------------------
 * matrix.hpp
 *
 * Copyright (c) 2017 Yann Herklotz Grave <ymherklotz@gmail.com> -- MIT License
 * See file LICENSE for more details
 * ----------------------------------------------------------------------------
 */

#ifndef YAGE_MATH_MATRIX_HPP
#define YAGE_MATH_MATRIX_HPP

#include <algorithm>
#include <exception>
#include <iostream>
#include <sstream>
#include <string>
#include <vector>

namespace yage
{

template<int Rows, int Cols, class Type> class Matrix;

// includes implementation details that should not be accessible to the user
namespace detail
{

// Row class
//
// Used to implement the double square bracket operator and be able
// to return the value by reference of the array.
template<int Rows, int Cols, class Type> class Row
{
private:
    Matrix<Rows, Cols, Type> *parent_;
    int index_;

public:
    Row<Rows, Cols, Type>(Matrix<Rows, Cols, Type> *parent, int index) :
        parent_(parent), index_(index)
    {}

    Type& operator[](int col)
    {
        // the index is the y-position of the element in the matrix
        return parent_->data_[index_*Cols+col];
    }

    const Type& operator[](int col) const
    {
        return parent_->data_[index_*Cols+col];
    }
};

} // detail

// Matrix class
//
// Implements the base Matrix class that is inherited by other classes to make them more
// specific.
template<int Rows=4, int Cols=4, class Type=double> class Matrix
{
    // friended with the row class so that it can access protected member data
    friend class detail::Row<Rows, Cols, Type>;
protected:
    std::vector<Type> data_;

public:
    Matrix<Rows, Cols, Type>() : data_(Rows*Cols) {}
    
    int rowSize() const
    {
        return Rows;
    }

    int colSize() const
    {
        return Cols;
    }

    // returns the row in a row matrix
    Matrix<1, Cols, Type> getRow(int row) const
    {
        Matrix<1, Cols, Type> rowMatrix;
        for(int i=0; i<Cols; ++i)
        {
            rowMatrix[0][i]=data_[row][i];
        }
        return rowMatrix;
    }

    // returns the column in a column matrix
    Matrix<Rows, 1, Type> getCol(int col) const
    {
        Matrix<Rows, 1, Type> colMatrix;
        for(int i=0; i<Rows; ++i)
        {
            colMatrix[i][0]=data_[i][col];
        }
        return colMatrix;
    }

    // iterator support for begin
    typename std::vector<Type>::iterator begin()
    {
        return data_.begin();
    }

    // iterator support for end
    typename std::vector<Type>::iterator end()
    {
        return data_.end();
    }

    // prints out the matrix, but can also be implemented by other classes to print data
    // differently
    virtual std::string toString() const
    {
        std::stringstream ss;
        ss<<'[';
        for(int i=0; i<Rows-1; ++i)
        {
            ss<<'[';
            for(int j=0; j<Cols-1; ++j)
            {
                ss<<data_[i*Cols+j]<<' ';
            }
            ss<<data_[(Rows-1)*Cols+Cols-1]<<"],";
        }
        ss<<'[';
        for(int j=0; j<Cols-1; ++j)
        {
            ss<<data_[(Rows-1)*Cols+j]<<' ';
        }
        ss<<data_[(Rows-1)*Cols+Cols-1]<<"]]";
        return ss.str();
    }

    detail::Row<Rows, Cols, Type> operator[](int row)
    {
        return detail::Row<Rows, Cols, Type>(this, row);
    }

    detail::Row<Rows, Cols, Type> operator[](int row) const
    {
        // TODO got to fix this
        return detail::Row<Rows, Cols, Type>((Matrix<Rows, Cols, Type>*)this, row);
    }

    Matrix<Rows, Cols, Type>& operator=(const Matrix<Rows, Cols, Type> &other)
    {
        if(this!=&other)
        {
            data_=other.data_;
        }
        return *this;
    }

    Matrix<Rows, Cols, Type>& operator+=(const Matrix<Rows, Cols, Type> &rhs)
    {
        std::vector<Type> out;
        out.reserve(data_.size());
        std::transform(data_.begin(), data_.end(), rhs.data_.begin(), std::back_inserter(out),
                       [] (Type a, Type b) {
                           return a+b;
                       });
        data_=std::move(out);
        return *this;
    }

    Matrix<Rows, Cols, Type>& operator-=(const Matrix<Rows, Cols, Type> &rhs)
    {
        std::vector<Type> out;
        out.reserve(data_.size());
        std::transform(data_.begin(), data_.end(), rhs.begin(), std::back_inserter(out),
                       [] (Type a, Type b) {
                           return a-b;
                       });
        data_=std::move(out);
        return *this;
    }
};

template<int M, int N, class T>
Matrix<M, N, T> operator+(Matrix<M, N, T> lhs, const Matrix<M, N, T> &rhs)
{
    lhs+=rhs;
    return lhs;
}

template<int M, int N, class T>
Matrix<M, N, T> operator-(Matrix<M, N, T> lhs, const Matrix<M, N, T> &rhs)
{
    lhs-=rhs;
    return lhs;
}

template<int M, int N, class T>
Matrix<M, N, T> operator+(Matrix<M, N, T> lhs, const T &rhs)
{
    for(auto &data : lhs)
    {
        data+=rhs;
    }
    return lhs;
}

template<int M, int N, class T>
Matrix<M, N, T> operator+(const T &lhs, Matrix<M, N, T> rhs)
{
    for(auto &data : rhs)
    {
        data+=lhs;
    }
    return rhs;
}

template<int M, int N, class T>
Matrix<M, N, T> operator-(Matrix<M, N, T> lhs, const T &rhs)
{
    for(auto &data : lhs)
    {
        data-=rhs;
    }
    return lhs;
}

template<int M, int N, class T>
Matrix<M, N, T> operator-(const T &lhs, Matrix<M, N, T> rhs)
{
    for(auto &data : rhs)
    {
        data=lhs-data;
    }
    return rhs;
}

template<int M, int N, class T>
Matrix<M, N, T> operator*(Matrix<M, N, T> lhs, const T &rhs)
{
    for(auto &data : lhs)
    {
        data*=rhs;
    }
    return lhs;
}

template<int M, int N, class T>
Matrix<M, N, T> operator*(const T &lhs, Matrix<M, N, T> rhs)
{
    for(auto &data : rhs)
    {
        data*=lhs;
    }
    return rhs;
}

template<int M, int N, class T>
Matrix<M, N, T> operator/(Matrix<M, N, T> lhs, const T &rhs)
{
    for(auto &data : lhs)
    {
        data/=rhs;
    }
    return lhs;
}

template<int M, int N, class T>
bool operator==(const Matrix<M, N, T> &lhs, const Matrix<M, N, T> &rhs)
{
    for(int i=0; i<M; ++i)
        for(int j=0; j<N; ++j)
            if(lhs[i][j]!=rhs[i][j])
                    return false;
    return true;
}

template<int M, int N, class T>
std::ostream& operator<<(std::ostream &os, const Matrix<M, N, T> &mat)
{
    return os<<mat.toString();
}

template<int Rows=2, class Type=double> class Vector : public Matrix<Rows, 1, Type>
{
public:
    Vector<Rows, Type>() : Matrix<Rows, 1, Type>() {}
    explicit Vector<Rows, Type>(const Matrix<Rows, 1, Type> &other) : Matrix<Rows, 1, Type>(other) {}

    Type& operator[](int col)
    {
        return this->data_[col];
    }

    const Type& operator[](int col) const
    {
        return this->data_[col];
    }

    virtual std::string toString() const
    {
        std::stringstream ss;
        ss<<"[";
        for(std::size_t i=0; i<this->data_.size()-1; ++i)
        {
            ss<<this->data_[i]<<" ";
        }
        ss<<this->data_[this->data_.size()-1]<<"]";
        return ss.str();
    }
};

template<class Type=double> class Vector2 : public Vector<2, Type>
{
public:
    Vector2<Type>() : Vector<2, Type>() {}
    
    Vector2<Type>(Type x, Type y)
    {
        this->data_[0]=x;
        this->data_[1]=y;
    }
    
    Vector2<Type>(const Matrix<2, 1, Type> &other) : Vector<2, Type>(other) {} 

    Type& x()
    {
        return this->data_[0];
    }

    const Type& x() const
    {
        return this->data_[0];
    }
    
    Type& y()
    {
        return this->data_[1];
    }

    const Type& y() const
    {
        return this->data_[1];
    }   
};

typedef Vector2<double> Vector2d;

namespace matrix
{

template<int M, int N, class T> Matrix<N, M, T> transpose(const Matrix<M, N, T> &m)
{
    Matrix<N, M, T> trans;
    for(int i=0; i<M; ++i)
    {
        for(int j=0; j<N; ++j)
        {
            trans[j][i]=m[i][j];
        }
    }
    return trans;
}

template<int R, class T> T dot(const Matrix<R, 1, T> &m1, const Matrix<R, 1, T> &m2)
{
    T sum=0;
    for(int i=0; i<R; ++i)
    {
        sum += m1[i][0]*m2[i][0];
    }
    return sum;
}

template<int M, int N, int P, int Q, class T>
Matrix<M, Q, T> multiply(const Matrix<M, N, T> &m1, const Matrix<P, Q, T> &m2)
{
    if(N!=P)
    {
        throw std::runtime_error("Matrices don't have the right dimensions for multiplication");
    }
    
    Matrix<M, Q, T> res;

    for(int i=0; i<M; ++i)
    {
        for(int j=0; j<Q; ++j)
        {
            res[i][j] = dot(transpose(m1.getRow(i)), m2.getCol(j));
        }
    }

    return res;
}

} // matrix

} // yage

#endif