numeric

cpp-eigen.cpp (581B)

---

 #include <iostream>
 #include <cstdlib>
 #include <eigen3/Eigen/Dense>
 
 int main(int argc, char* argv[])
 {
     using std::cout;
     using Eigen::MatrixXd;
 
     unsigned int N, i, j;
 
     if (argc == 2) {
         N = atoi(argv[1]);
     } else {
         std::cerr << "Sorry, I need matrix width as command line argument\n";
         return 1;
     }
 
     MatrixXd A(N,N);
     MatrixXd B(N,N);
     MatrixXd C(N,N);
 
     for (i = 0; i<N; ++i) {
         for (j = 0; j<N; ++j) {
             A(i,j) = 2.0;
             B(i,j) = (double) N*j + i;
         }
     }
 
     C = A*B;
 
     return 0;
 }