I am using Ubuntu 18.04 and g++. I am getting the following while trying to use the Eigen Library

In file included from /usr/include/c++/7/unsupported/Eigen/IterativeSolvers:29:0,
from numeric.h:24:
/usr/include/c++/7/unsupported/Eigen/src/IterativeSolvers/ConstrainedConjGrad.h: In function ‘void Eigen::internal::constrained_cg(const TMatrix&, const CMatrix&, VectorX&, const VectorB&, const VectorF&, Eigen::IterationController&)’:
/usr/include/c++/7/unsupported/Eigen/src/IterativeSolvers/ConstrainedConjGrad.h:162:51: error: ‘cerr’ is not a member of ‘std’
if (iter.noiseLevel() > 0 && transition) std::cerr << "CCG: transition\n";
^~~~
/usr/include/c++/7/unsupported/Eigen/src/IterativeSolvers/ConstrainedConjGrad.h:162:51: note: suggested alternative: ‘errc’
if (iter.noiseLevel() > 0 && transition) std::cerr << "CCG: transition\n";
^~~~
errc

Regards,
SLB