Exception thrown: access violation (eigen matrix class)

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So, I'm using the Eigen matrix library (version 3.3.7), and I'm trying to test things out and see that everything's going fine. However, on the test program below:

What I have tried:

C++

#include <iostream>
#include <sstream>

#include <Eigen/Dense>

using namespace std;
using namespace Eigen;

int main()
{
	cout << "Hello World!" << endl;

	MatrixXd A;
	A << 1, 2, 3,
		4, 5, 6,
		7, 8, -9;

	cout << A << endl;

	cin.get();
	return 0;
}

I'm getting an error:

<pre>"Exception thrown at 0x________ in Matrices.exe: 0xC0000005: Access violation writing location 0x00000000."

Oddly enough, everything goes fine if I initialise a Matrix3d instead of a MatrixXd. Could anyone help me and figure out how to fix this?

Posted 28-Mar-19 13:27pm

uarc40960

Updated 28-Mar-19 15:26pm

v2

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MadMyche 28-Mar-19 20:08pm

How are you compiling this?

uarc40960 28-Mar-19 20:39pm

Visual Studio

1 solution

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Rick York · Accepted Answer · 2019-03-28T15:26:00

Solution 1

This works for me:

C++

Eigen::MatrixXd a( 3, 3 );
a << 1, 2, 3,
     4, 5, 6,
     7, 8, 9;

std::stringstream s;
s << a;

trace( "%s\n", s.str().data() );

trace is the output function I use in my apps. The issue is MatrixXd is a dynamic matrix and you have to tell it how big the matrix is first.

Posted 28-Mar-19 15:26pm

Rick York

Comments

uarc40960 28-Mar-19 21:43pm

Thanks SO MUCH!

Maciej Los 29-Mar-19 13:30pm

5ed!

Rick York 29-Mar-19 14:00pm

Thank you sir.