  The Scaled Relative Graph (SRG) by Ryu, Hannah, and Yin (arXiv:1902.09788,
2019) is a geometric tool that maps the action of a multi-valued nonlinear
operator onto the 2D plane, used to analyze the convergence of a wide range of
iterative methods. As the SRG includes the spectrum for linear operators, we
can view the SRG as a generalization of the spectrum to multi-valued nonlinear
operators. In this work, we further study the SRG of linear operators and
characterize the SRG of block-diagonal and normal matrices.
