diff --git a/lab06/matrix.h b/lab06/matrix.h
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+++ b/lab06/matrix.h
@@ -0,0 +1,343 @@
+/**
+ * matrix.h a very simplistic class for m times n matrices.
+ */
+
+#ifndef MATRIX_H
+#define MATRIX_H
+
+#include <vector>
+#include <iostream>
+#include <iomanip>
+#include <cmath>
+
+// A very simplistic vector class for vectors of size n
+class Vector {
+ public:
+  // constructors
+  Vector(int n) : n_(n), data_(n_, 0) {}
+  Vector(const Vector& other) = default;
+  Vector(Vector&& other) = default;
+  ~Vector() = default;
+
+  // assignment operators
+  Vector& operator=(const Vector& other) = default;
+  Vector& operator=(Vector&& other) = default;
+
+  // element access
+  double& operator()(int i) { return data_[i]; }
+  const double& operator()(int i) const { return data_[i]; }
+
+  // getter functions for the dimensions
+  int dim() const { return n_; }
+
+  // comparison operators
+  bool operator==(const Vector& b) { return (data_ == b.data_); }
+  bool operator!=(const Vector& b) { return (data_ != b.data_); }
+
+  // addition
+  Vector& operator+=(const Vector& b) {
+    for (int i = 0; i < n_; ++i) {
+      operator()(i) += b(i);
+    }
+    return *this;
+  }
+
+  // subtraction
+  Vector& operator-=(const Vector& b) {
+    for (int i = 0; i < n_; ++i) {
+      operator()(i) -= b(i);
+    }
+    return *this;
+  }
+
+  // scalar multiplication
+  Vector& operator*=(double x) {
+    for (int i = 0; i < n_; ++i) {
+      operator()(i) *= x;
+    }
+    return *this;
+  }
+
+  // dot product between two vectors
+  double dot(const Vector& other) const {
+    double sum = 0;
+    for (int i = 0; i < n_; ++i) {
+      sum += operator()(i) * other(i);
+    }
+    return sum;
+  }
+
+ private:
+  int n_;                     // vector dimension
+  std::vector<double> data_;  // the vectors entries
+};
+
+inline double dot(const Vector& v1, const Vector& v2) {
+  return v1.dot(v2);
+}
+
+// Print the vector as a table
+inline std::ostream& operator<<(std::ostream& os, const Vector& a) {
+  const int width = 10;
+  const int precision = 4;
+
+  const auto originalPrecision = os.precision();
+  os << std::setprecision(precision);
+
+  for (int i = 0; i < a.dim(); ++i) {
+    os << std::setw(width) << a(i) << " ";
+  }
+
+  os << "\n";
+
+  os << std::setprecision(originalPrecision);
+  return os;
+}
+
+// A very simple class for m times n matrices
+class Matrix {
+ public:
+  // constructors
+  Matrix() : Matrix(0, 0) {}
+  Matrix(int m, int n) : m_(m), n_(n), data_(m_ * n_, 0) {}
+  Matrix(std::pair<int, int> dim) : Matrix(dim.first, dim.second) {}
+  Matrix(int n) : Matrix(n, n) {}
+  Matrix(const Matrix& other) = default;
+  Matrix(Matrix&& other) = default;
+  ~Matrix() = default;
+
+  // assignment operators
+  Matrix& operator=(const Matrix& other) = default;
+  Matrix& operator=(Matrix&& other) = default;
+
+  // element access
+  double& operator()(int i, int j) { return data_[i * n_ + j]; }
+  const double& operator()(int i, int j) const { return data_[i * n_ + j]; }
+
+  // getter functions for the dimensions
+  std::pair<int, int> dim() const { return std::pair<int, int>(m_, n_); }
+  int dim1() const { return m_; }
+  int dim2() const { return n_; }
+  int numEntries() const { return data_.size(); }
+
+  // comparison operators
+  bool operator==(const Matrix& b) { return (data_ == b.data_); }
+  bool operator!=(const Matrix& b) { return (data_ != b.data_); }
+
+  // addition
+  Matrix& operator+=(const Matrix& b) {
+    for (int i = 0; i < m_; ++i) {
+      for (int j = 0; j < n_; ++j) {
+        operator()(i, j) += b(i, j);
+      }
+    }
+    return *this;
+  }
+
+  // subtraction
+  Matrix& operator-=(const Matrix& b) {
+    for (int i = 0; i < m_; ++i) {
+      for (int j = 0; j < n_; ++j) {
+        operator()(i, j) -= b(i, j);
+      }
+    }
+    return *this;
+  }
+
+  // scalar multiplication
+  Matrix& operator*=(double x) {
+    for (int i = 0; i < m_; ++i) {
+      for (int j = 0; j < n_; ++j) {
+        operator()(i, j) *= x;
+      }
+    }
+    return *this;
+  }
+
+  // scalar division
+  Matrix& operator/=(double x) {
+    for (int i = 0; i < m_; ++i) {
+      for (int j = 0; j < n_; ++j) {
+        operator()(i, j) /= x;
+      }
+    }
+    return *this;
+  }
+
+  // matrix product (only for square matrices of equal dimension)
+  Matrix& operator*=(const Matrix& b) {
+    if (dim1() != dim2()) {
+      std::cout << "Error in matrix multiplication: no square matrix\n";
+    } else if (dim1() != b.dim1() || dim2() != b.dim2()) {
+      std::cout << "Error in matrix multiplication: dimensions do not match\n";
+    } else {
+      Matrix a = *this;
+      Matrix& c = *this;
+      const int m = dim1();
+      for (int i = 0; i < m; ++i) {
+        for (int j = 0; j < m; ++j) {
+          for (int k = 0; k < m; ++k) {
+            c(i, j) += a(i, k) * b(k, j);
+          }
+        }
+      }
+    }
+
+    return *this;
+  }
+
+ public:
+  int m_;                     // first dimension
+  int n_;                     // second dimension
+  std::vector<double> data_;  // the matrix' entries
+};
+
+// Print the matrix as a table
+inline std::ostream& operator<<(std::ostream& os, const Matrix& a) {
+  const int width = 10;
+  const int precision = 4;
+
+  const auto originalPrecision = os.precision();
+  os << std::setprecision(precision);
+
+  for (int i = 0; i < a.dim1(); ++i) {
+    for (int j = 0; j < a.dim2(); ++j) {
+      os << std::setw(width) << a(i, j) << " ";
+    }
+    if (i != a.dim1() - 1)
+      os << "\n";
+  }
+
+  os << std::setprecision(originalPrecision);
+  return os;
+}
+
+// matrix product
+inline Matrix operator*(const Matrix& a, const Matrix& b) {
+  if (a.dim2() == b.dim1()) {
+    int m = a.dim1();
+    int n = a.dim2();
+    int p = b.dim2();
+    Matrix c(m, p);
+    for (int i = 0; i < m; ++i) {
+      for (int j = 0; j < p; ++j) {
+        for (int k = 0; k < n; ++k) {
+          c(i, j) += a(i, k) * b(k, j);
+        }
+      }
+    }
+    return c;
+  } else {
+    return Matrix(0, 0);
+  }
+}
+
+inline bool equalWithinRange(const Matrix& a,
+                             const Matrix& b,
+                             double eps = 1e-12) {
+  if (a.dim1() != b.dim1() || a.dim2() != b.dim2())
+    return false;
+
+  int m = a.dim1();
+  int n = a.dim2();
+  for (int i = 0; i < m; ++i) {
+    for (int j = 0; j < n; ++j) {
+      if (fabs(a(i, j) - b(i, j)) > eps) {
+        return false;
+      }
+    }
+  }
+
+  return true;
+}
+
+// A very simple class for "3D-Matrices" (tensors) with dimension l x m x n
+class Matrix3D {
+ public:
+  // constructors
+  Matrix3D(int l, int m, int n) : l_(l), m_(m), n_(n), data_(l) {
+    for (int i = 0; i < l_; ++i) {
+      data_[i] = std::vector<std::vector<double>>(m_);
+      for (int j = 0; j < m_; ++j) {
+        data_[i][j] = std::vector<double>(n_, 0);
+      }
+    }
+  }
+  Matrix3D(int n) : Matrix3D(n, n, n) {}
+  Matrix3D(const Matrix3D& other) = default;
+  Matrix3D(Matrix3D&& other) = default;
+  ~Matrix3D() = default;
+
+  // assignment operators
+  Matrix3D& operator=(const Matrix3D& other) = default;
+  Matrix3D& operator=(Matrix3D&& other) = default;
+
+  // element access
+  double& operator()(int i, int j, int k) { return data_[i][j][k]; }
+  const double& operator()(int i, int j, int k) const { return data_[i][j][k]; }
+
+  // getter functions for the dimensions
+  int dim1() const { return l_; }
+  int dim2() const { return m_; }
+  int dim3() const { return n_; }
+
+  // comparison operators
+  bool operator==(const Matrix3D& b) { return (data_ == b.data_); }
+  bool operator!=(const Matrix3D& b) { return (data_ != b.data_); }
+
+  // addition
+  Matrix3D& operator+=(const Matrix3D& b) {
+    for (int i = 0; i < l_; ++i) {
+      for (int j = 0; j < m_; ++j) {
+        for (int k = 0; k < n_; ++k) {
+          operator()(i, j, k) += b(i, j, k);
+        }
+      }
+    }
+    return *this;
+  }
+
+  // substraction
+  Matrix3D& operator-=(const Matrix3D& b) {
+    for (int i = 0; i < l_; ++i) {
+      for (int j = 0; j < m_; ++j) {
+        for (int k = 0; k < n_; ++k) {
+          operator()(i, j, k) -= b(i, j, k);
+        }
+      }
+    }
+    return *this;
+  }
+
+  // scalar multiplication
+  Matrix3D& operator*=(double x) {
+    for (int i = 0; i < l_; ++i) {
+      for (int j = 0; j < m_; ++j) {
+        for (int k = 0; k < n_; ++k) {
+          operator()(i, j, k) *= x;
+        }
+      }
+    }
+    return *this;
+  }
+
+  // scalar division
+  Matrix3D& operator/=(double x) {
+    for (int i = 0; i < l_; ++i) {
+      for (int j = 0; j < m_; ++j) {
+        for (int k = 0; k < n_; ++k) {
+          operator()(i, j, k) /= x;
+        }
+      }
+    }
+    return *this;
+  }
+
+ private:
+  int l_;                                               // first dimension
+  int m_;                                               // second dimension
+  int n_;                                               // third dimension
+  std::vector<std::vector<std::vector<double>>> data_;  // the tensors' entries
+};
+
+#endif  // MATRIX_H
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