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Function "Invert()" now inverts a matrix

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Robert Altner 2019-01-24 04:11:32 +01:00
parent 08c502e99f
commit 86643012e2
2 changed files with 88 additions and 16 deletions
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71
Matrix/Matrix.hpp
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@ -30,6 +30,8 @@ public:
// Constructional functions
friend void Zero(Matrix& mat);
friend void Identity(Matrix& mat);
friend Matrix Identity(uint dimension);
// Setters / Getters
@ -47,6 +49,7 @@ public:
// Transformation / arithmetic functions
void Transpose();
void Invert();
void MultiplyRow(uint row, double factor);
void SwapRows(uint left, uint right);
void AddMultiplesToRow(uint base, uint target, double factor);
@ -54,6 +57,9 @@ public:
void TransformToEchelonForm();
void TransformToReducedEchelonForm();
void ConcatVertically(const Matrix& other);
void ConcatHorizontally(const Matrix& other);
friend double det(const Matrix& mat);
friend Matrix mul(const Matrix& left, const Matrix& right);
@ -139,6 +145,18 @@ inline void Identity(Matrix& mat)
mat.m_matrix[k][k] = 1;
}
////////////////////////////////////////////////////
/// \brief Creates an identity matrix and returns it
///
////////////////////////////////////////////////////
inline Matrix Identity(uint dimension)
{
Matrix id(dimension, dimension);
Identity(id);
return id;
}
////////////////////////////////////////////////////
/// \brief Sets the number at a given position to a given value
@ -251,6 +269,29 @@ inline void Matrix::Transpose()
}
////////////////////////////////////////////////////
/// \brief Inverts the matrix
///
////////////////////////////////////////////////////
inline void Matrix::Invert()
{
if (!IsInvertable())
return;
Matrix holder = *this;
holder.ConcatVertically(Identity(m_rows));
holder.TransformToReducedEchelonForm();
Matrix inverse(m_rows, m_cols);
for (int row = 0; row < m_rows; row++)
for (int col = 0; col < m_cols; col++)
inverse.SetNumber(row, col, holder.GetNumber(row, col + m_cols));
*this = inverse;
}
////////////////////////////////////////////////////
/// \brief Multiplies each value of a given row by a given factor
///
@ -338,7 +379,7 @@ inline Matrix mul(const Matrix& right, const Matrix& left)
for (uint row = 0; row < returnMatrix.m_rows; row++)
for (uint col = 0; col < returnMatrix.m_cols; col++)
for (uint k = 0; k < right.m_cols; k++)
for (uint k = 0; k < right.m_cols; k++)
returnMatrix.m_matrix[row][col] += right.m_matrix[row][k] * left.m_matrix[k][col];
return returnMatrix;
@ -491,6 +532,31 @@ inline void Matrix::TransformToReducedEchelonForm()
if (m_matrix[row][col] == -0) m_matrix[row][col] = 0;
}
inline void Matrix::ConcatVertically(const Matrix& other)
{
if (m_rows != other.GetRows())
return;
Resize(m_rows, m_cols + other.GetColumns(), m_matrix);
for (int row = 0; row < m_rows; row++)
for (int col = other.GetColumns(); col < m_cols; col++)
m_matrix[row][col] = other.GetNumber(row, col - other.GetColumns());
}
inline void Matrix::ConcatHorizontally(const Matrix& other)
{
if (m_cols != other.GetColumns())
return;
Resize(m_rows + other.GetRows(), m_cols, m_matrix);
for (int col = 0; col < m_cols; col++)
for (int row = other.GetRows(); row < m_rows; row++)
m_matrix[row][col] = other.GetNumber(row, col - other.GetColumns());
}
inline bool Matrix::InBounds(uint row, uint col) const
{
@ -510,6 +576,9 @@ inline void Matrix::Resize(uint rows, uint cols, doubleMatrix& matrix)
matrix.resize(rows);
for (int row = 0; row < rows; row++)
matrix[row].resize(cols);
m_rows = rows;
m_cols = cols;
}

33
Matrix/main.cpp
View file

@ -8,24 +8,27 @@ int main(int argc, char** argv)
std::default_random_engine engine(time(NULL));
std::uniform_int_distribution<int> range(0, 4);
Matrix myMatrix(4, 4);
for (int row = 0; row < 3; row++)
for (int col = 0; col < 4; col++)
myMatrix.SetNumber(row, col, range(engine));
// Hardcode a matrix
Matrix myMatrix(3, 3);
myMatrix.SetNumber(0, 0, 1);
myMatrix.SetNumber(0, 1, 1);
myMatrix.SetNumber(0, 2, 1);
myMatrix.SetNumber(1, 0, 0);
myMatrix.SetNumber(1, 1, 1);
myMatrix.SetNumber(1, 2, 1);
myMatrix.SetNumber(2, 0, 0);
myMatrix.SetNumber(2, 1, 0);
myMatrix.SetNumber(2, 2, 1);
Matrix otherMatrix(4, 4);
Identity(otherMatrix);
Matrix inverse = myMatrix;
inverse.Invert();
Matrix addMatrix = myMatrix * otherMatrix;
std::cout << myMatrix << std::endl;
std::cout << myMatrix;
std::cout << std::endl << "-" << std::endl << std::endl;
std::cout << otherMatrix;
std::cout << std::endl << "=" << std::endl << std::endl;
std::cout << addMatrix << std::endl;
std::cout << det(addMatrix) << std::endl;
std::cout << addMatrix.IsInvertable() << std::endl;
std::cout << std::endl;
std::cout << inverse << std::endl;
std::cout << mul(myMatrix, inverse) << std::endl;
getchar();