On pp. 152-3 of Hydon's *Symmetry Methods for Differential Equations* (2000 ed.), he lists some computer packages for symmetry-finding. This related Mathematica StackExchange question mentions the SYM Mathematica package and Maple's DEtools/symgen. Does SAGE have anything similar for doing symmetry-finding?

^{This question also posted on ask.sagemath.org}