C++ Armadillo :: Accessing row and column and operations on it
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Description::
This is the basic C++ program of C++ armadillo library which shows how to access rows and column of the given matrix. It can be carried out by the help of inbuilt functions "row" or "col" in armadillo library. Both the function do not take any parametres. Elements can be made zero by function "zeros".
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Program::
#include <iostream>
#include <armadillo>using namespace std;
using namespace arma;
int main(int argc, const char **argv)
{
//initialize the random generator
//Create a 4 x 4 random matrix and printing it
mat A = randu<mat>(4,4); //random matrix of size 4x4 (generared by this syntax)
cout << "Matrix A::\n"<<endl;
cout<< A << endl; cout << A.row(0) << "\n"; //Displaying first row
A.row(0) = A.row(1) + A.row(3); //Addition of rows
cout << "Matrix A(After operation)::\n"<<endl;
cout<< A << endl;
// Accessing second column of matrix A
cout << "Column 2::\n"<<endl; //Displaying second column
cout << A.col(1) << "\n";
// Making all the elements of third column of matrix A to zero
A.col(2).zeros(); //Making all the elements zero
cout << "Matrix A(After operation)::\n"<<endl;
cout<< A << endl;
return 0;
}
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Commands to run program on terminal::
$ g++ filename.cpp -o objectname -O2 -larmadillo
$ ./objectname
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Output::
Matrix A::
0.7868 0.0193 0.5206 0.1400
0.2505 0.4049 0.3447 0.5439
0.7107 0.2513 0.2742 0.5219
0.9467 0.0227 0.5610 0.8571
Row 1::
0.7868 0.0193 0.5206 0.1400
Matrix A(After operation)::
1.1971 0.4276 0.9057 1.4009
0.2505 0.4049 0.3447 0.5439
0.7107 0.2513 0.2742 0.5219
0.9467 0.0227 0.5610 0.8571
Column 2::
0.4276
0.4049
0.2513
0.0227
Matrix A(After operation)::
1.1971 0.4276 0 1.4009
0.2505 0.4049 0 0.5439
0.7107 0.2513 0 0.5219
0.9467 0.0227 0 0.8571
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