Getting error including eigen library in c++ - c++

Question

I am trying to use eigen for linear algebra but can't get it to include the eigen library. It keeps on giving me an error even though I am following all the instructions to include the eigen folder while compiling the program. I have tried this in both visual studio 2017 and the MinGW version of gcc. I am giving the relevant part of my code and what I am doing to include the Eigen library.
#include <iostream>
#include <fstream>
using namespace std;
#include <Eigen/Dense>
using Eigen::MatrixXd;
int main()
{
MatrixXd m(2,2);
m(0,0) = 3;
m(1,0) = 2.5;
m(0,1) = -1;
m(1,1) = m(1,0) + m(0,1);
std::cout << m << std::endl;
}
To run this in g++, I am using the command
g++ -I /C:\Users\aqils\Documents\C++\Eigen/ Matrixbasics.cpp -o Matrixbasics.exe
Here C:\Users\aqils\Documents\C++\Eigen
is the path for the unzipped Eigen package.
Matrixbasics.cpp is the name of the c++ file and it's located in the folder
C:\Users\aqils\Documents\C++
The error I get is
"Fatal error: Eigen/Dense: no such file or directory"
To run this in Visual Studio 2017, I have followed these steps to add a folder to a project:
1. Right click on the project name in the solution explorer and hit properties
2. Then look for c++ and find the option for adding a folder.
3. Select the Eigen package folder in the tree view, hit ok and then apply.
4. Run the program. It should now work.
I have spent several frustrating days trying to make this work and have read all related questions on stack overflow as well as several other websites. The answers don't go beyond the above instructions which I am already following. Will be really grateful if someone can help me fix the problem.

Answer 1

You can replace this line:
#include <Eigen/Dense>
by:
#include <eigen3/Eigen/Dense>