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  1. #include <iostream>
  2. #include <array>
  3.  
  4. template <size_t N, size_t M>
  5. struct Matrix {
  6. 	  std::array<std::array<double, M>, N> data_;
  7.  
  8. 	  std::array<double, M>& operator [] (size_t index) { 
  9. 	  	return data_[index]; 
  10. 	  }
  11. 	  std::array<double, M> operator [] (size_t index) const { 
  12. 	  	return const_cast<Matrix&>(*this)[index]; 
  13. 	  }
  14.  
  15. 	  template <size_t I, size_t J, size_t K>
  16. 	  friend Matrix<I,K> operator* (const Matrix<I,J>&, const Matrix<J,K>&);
  17. };	
  18.  
  19. template <size_t Size>
  20. struct Vector : public Matrix <1,Size> {
  21. 	  double& operator [] (size_t index) { 
  22. 	  	return Matrix<1,Size>::data_[0][index]; 
  23. 	  }
  24. 	  double operator [] (size_t index) const { 
  25. 	  	return const_cast<Vector&>(*this)[index]; 
  26. 	  }
  27. };
  28.  
  29. template <size_t I, size_t J, size_t K>
  30. Matrix<I,K> operator* (const Matrix<I,J>& lhs, const Matrix<J,K>& rhs) {
  31. 	Matrix<I,K> r;
  32. 	for (size_t i=0; i < I; ++i)
  33. 	   for (size_t k=0; k < K; ++k) {
  34. 	  	r[i][k]=0;
  35. 	    for (size_t j=0; j < J; ++j)
  36. 	      r[i][k] += lhs[i][j]*rhs[j][k];
  37. 	  }
  38.  
  39. 	return r;
  40. }
  41.  
  42. template <typename T, size_t N>
  43. std::ostream& operator <<(std::ostream& os, const std::array<T,N>& a) {
  44. 	os << '(';
  45. 	size_t i=0;
  46. 	for (auto x: a) {
  47. 		if (i++ != 0) os << ',';
  48. 		os << x;
  49. 	}
  50. 	os << ')';
  51. 	return os;
  52. }
  53.  
  54. template <size_t N, size_t M>
  55. std::ostream& operator <<(std::ostream& os, const Matrix<N,M>& m) {
  56. 	return os << m.data_;
  57. }
  58.  
  59. int main() {
  60. 	Vector<3> v;
  61. 	v[0] = 1; v[1] = 2; v[2] = 3;
  62. 	std::cout << "v=" << v << std::endl;
  63.  
  64. 	Matrix<3,2> m;
  65. 	m[0][0]=1;m[0][1]=2;
  66. 	m[1][0]=3;m[1][1]=4;
  67. 	m[2][0]=5;m[2][1]=6;
  68. 	std::cout << "m=" << m << std::endl;
  69.  
  70. 	Matrix<2,4> m1;
  71. 	m1[0][0]=1;m1[0][1]=2;m1[0][2]=3;m1[0][3]=4;
  72. 	m1[1][0]=5;m1[1][1]=6;m1[1][2]=7;m1[1][3]=8;
  73. 	std::cout << "m1=" << m1 << std::endl;
  74.  
  75. 	std::cout << "m*m1=" << m*m1 << std::endl;
  76. 	std::cout << "v*m=" << v*m << std::endl;
  77. }
Success #stdin #stdout 0s 3344KB
comments (?)
stdin 
Standard input is empty
stdout 
v=((1,2,3))
m=((1,2),(3,4),(5,6))
m1=((1,2,3,4),(5,6,7,8))
m*m1=((11,14,17,20),(23,30,37,44),(35,46,57,68))
v*m=((22,28))
https://ideone.com/yu7dcf
language:
C++14 (gcc 8.3)
created:
12 years ago
visibility:
public

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