• My test code runs successfully on MS VS2008.
    This is from the website:
    "Eigen is standard C++98 and so should theoretically be compatible with any compliant compiler. Whenever we use some non-standard feature, that is optional and can be disabled.

Eigen is being successfully used with the following compilers:

    • GCC, version 4.1 and newer. Very good performance with GCC 4.2 and newer.
    • MSVC (Visual Studio), 2008 and newer (the old 2.x versions of Eigen support MSVC 2005, but without vectorization).
    • Intel C++ compiler. Very good performance.
    • LLVM/CLang++ (2.8 and newer).
    • MinGW, recent versions. Very good performance when using GCC 4.
    • QNX's QCC compiler.
  • The shown compiler error is in my case the same for default and relaxed ANSI language mode. I changed to relaxed ANSI, ok.
  • Hopefully this source code gives a better idea what's going on:

Ausgleichsgerade.cpp

#include "Ausgleichsgerade.h"
#define EIGEN_DONT_USE_RESTRICT_KEYWORD
#include "Eigen/Core"

void test()
{
    Eigen::MatrixXd A(2,3);
    A << 1, 2, 3, 0, 0, 1;
    Eigen::MatrixXd B;
    B = A * A.transpose();
}

Precompiler output:

Ausgleichsgerade.pp

(Please visit the site to view this file)