title: How to compare vectors approximately in Eigen?
body: <p>Is there a function in Eigen to compare vectors (matrices) using both relative and absolute tolerance aka <a href="http://docs.scipy.org/doc/numpy/reference/generated/numpy.allclose.html">numpy.allclose</a>? Standard <a href="http://eigen.tuxfamily.org/dox/classEigen_1_1DenseBase.html#a710e3763df8518854578a160c1a8902d">isApprox</a> fails if one of the vectors is very close to zero.</p>