#include "mtl/matrix.h"#include "mtl/mtl.h"#include "mtl/utils.h"  #include "mtl/linalg_vec.h"/*Sample outputA =5x5[[1,2,0,0,0],[2,3,4,0,0],[0,4,5,6,0],[0,0,6,7,8],[0,0,0,8,9]]x =[1,2,3,4,5,]y =[1,1,1,1,1,]Ax + y =[13,43,97,175,157,]    */using namespace mtl;intmain(){  //begin  typedef matrix< double, symmetric<lower>, banded<>, row_major>::type Matrix;   typedef dense1D<double> Vec;  typedef Matrix::size_type Int;  const Int matrix_size = 5;  const Int band_size = 1;  Matrix A(matrix_size, band_size);  Vec y(matrix_size,1),x(matrix_size);  double alpha=2, beta=3;  //            1  2                 1        1  //            2  3  4              2        1  //       A =     4  5  6       x = 3    y = 1  //                  6  7  8        4        1  //                     8  9        5        1  //make A  Int r = 0, i = 0;  for (r = 0; r < matrix_size - 1; ++r){    A(r,r) = ++i;    A(r,r+1) = ++i;  }  A(r,r) = ++i;  //make x  for (i=0;i<matrix_size;++i)    x[i]=i+1;  //end  std::cout << "A =" << std::endl;  print_all_matrix(A);  std::cout << "x =" << std::endl;  print_vector(x);  std::cout << "y =" << std::endl;  print_vector(y);  //begin  mult(A,scaled(x,alpha),scaled(y,beta),y);  //end  std::cout << "Ax + y =";  print_vector(y);}