[eigen] Aligned Fixed Sized Mapped matrices

[Sameer Agarwal <sameeragarwal@xxxxxxxxxx>]

I was playing with mapping small fixed aligned buffers to fixed sized matrices and encountered an interesting eigen assertion failure in MapBase.h

Line 190 MapBase.h:

eigen_assert((   ((internal::UIntPtr(m_data) % internal::traits<Derived>::Alignment) == 0)

                    || (cols() * rows() * innerStride() * sizeof(Scalar)) < internal::traits<Derived>::Alignment ) && "data is not aligned");

I am particularly curious about the requirement

(cols() * rows() * innerStride() * sizeof(Scalar)) < internal::traits<Derived>::Alignment

Why this rather strict requirement?

Sameer