“…Continuous-stage Runge-Kutta methods (csRK methods, hereafter), introduced by Butcher [1][2][3], have been used in recent years as a useful tool for studying structurepreserving methods for Hamiltonian problems (see, e.g., [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]). In particular, we shall at first consider methods, within this latter class, having Butcher tableau in the form:…”