matrix multiplication implemented

Author: potat-dev

Variants/Lab_12/var_12/main.cpp

@@ -144,4 +144,28 @@ int main() {
 
   Matrix summ = Matrix(5, 1) + Matrix(5, 2);
   summ.print();
+  summ -= Matrix(5, 4);
+  summ.print();
+
+  // проверка умножения
+
+  Matrix mult1({
+    {1, 2, 3},
+    {4, 5, 6},
+    {7, 8, 9},
+  });
+  
+  Matrix mult2({
+    {6, 1, 8},
+    {0, 4, 2},
+    {6, 1, 8},
+  });
+
+  mult1.print();
+  cout << "  *\n" << endl;
+  mult2.print();
+
+  cout << "  =\n" << endl;
+  mult1 *= mult2;
+  mult1.print();
 }

Variants/Lab_12/var_12/matrix.cpp

@@ -140,7 +140,50 @@ Matrix& Matrix::operator+=(const Matrix& m) {
   return *this;
 }
 
+Matrix& Matrix::operator-=(const Matrix& m) {
+  try {
+    if (arr.size() == m.arr.size()) {
+      for (int x = 0; x < m.arr.size(); x++) {
+        for (int y = 0; y < m.arr.size(); y++) {
+          arr[y][x] -= m.arr[y][x];
+        }
+      }
+    } else {
+      throw "Matrices have different sizes";
+    }
+  } catch (const char *s) {
+    cerr << "Error in + operator: " << s << endl;
+    exit(1);
+  }
+  return *this;
+}
+
 Matrix operator+(Matrix a, const Matrix& b) {
   a += b;
   return a;
+}
+
+Matrix operator-(Matrix a, const Matrix& b) {
+  a -= b;
+  return a;
+}
+
+Matrix& Matrix::operator*=(const Matrix& right) {
+  unsigned int size = this->size();
+  Matrix result(size, 0);
+  for (int result_x = 0; result_x < size; result_x++) {
+    for (int result_y = 0; result_y < size; result_y++) {
+      double summ = 0;
+      for (int i = 0; i < size; i++)
+        summ += arr[result_y][i] * right.arr[i][result_x];
+      result.arr[result_y][result_x] = summ;
+    }
+  }
+  *this = result;
+  return *this;
+}
+
+Matrix operator*(Matrix a, const Matrix& b) {
+  a *= b;
+  return a;
 }

Variants/Lab_12/var_12/matrix.h

@@ -11,13 +11,16 @@ class Matrix {
     vector <vector <double>> arr;
 
   public:
+    // конструтроры (не лего)
     Matrix(unsigned int size = 1, double def = 0);
-    Matrix(vector <vector <double>> temp);
+    Matrix(vector <vector <double>> temp); 
 
+    // сеттеры
     Matrix& set(unsigned int x, unsigned int y, double value);
     Matrix& set(vector <vector <double>> temp);
     Matrix& set(Matrix& m);
 
+    // геттеры
     double get(unsigned int x, unsigned int y);
     const unsigned int size();
 
@@ -30,6 +33,10 @@ class Matrix {
     // операторы
 
     Matrix& operator+=(const Matrix& x);
+    Matrix& operator-=(const Matrix& x);
+    Matrix& operator*=(const Matrix& x);
+    
     friend Matrix operator+(Matrix a, const Matrix &b);
-
+    friend Matrix operator-(Matrix a, const Matrix &b);
+    friend Matrix operator*(Matrix a, const Matrix &b);
 };