Arch Linux

Description:

There are multiple versions of eigen library (version 2 and 3) and it installs in /usr/include/eigen2 and /usr/include/eigen3 respectively. If we try to use the headers from eigen library it throws the following error:

fatal error: Eigen/Dense: No such file or directory

Additional info:
* package version(s): eigen3 eigen2
* test.cpp

#include <fstream>
#include <iostream>
#include <Eigen/Dense>
using namespace std;

int main()
{
char str[10];

//Creates an instance of ofstream, and opens example.txt
ofstream a_file ( "example.txt" );
// Outputs to example.txt through a_file
a_file<<"This text will now be inside of example.txt";
// Close the file stream explicitly
a_file.close();
//Opens for reading the file
ifstream b_file ( "example.txt" );
//Reads one string from the file
b_file>> str;
//Should output 'this'
cout<< str <<"\n";
cin.get(); // wait for a keypress
// b_file is closed implicitly here
}


Steps to reproduce:
* Install eigen3 package using pacman -S eigen3
* Create a test.cpp file which uses an Eigen header
* Try to compile and compilation fails resulting in fatal error: No such file or directory found

Steps to solve:
* Provide a symlink of /usr/include/eigen3/Eigen to /usr/include/Eigen
* It successfully compiles