On Recent Advances of Spectral Analysis for Systems Arising From Fully‐Implicit RK Methods

ABSTRACT This work deals with two groups of spectral analysis results for matrices arising in fully implicit Runge–Kutta methods used for linear time‐dependent partial differential equations. These were applied to different formulations of the same problem and used different tools to arrive at results that do not immediately coincide. We show the equivalence of the results as well as the equivalence of the approaches, unifying the two directions.