Hello, I'm trying to debug a program, and the problems is that the terms in a sum are not ordered in the same way in every run. for example : 1 run : A+B+C gives A+B+C 2 run : A+B+C gives C+B+A ... I know that the 2 expressions are equal but I will like GiNaC to represent the expression always in the same way. It's only for debugging so I don't care about performance. Thanks Felipe -- Felipe Bordeu Weldt Ingénieur de Recherche ------------------------------------- Tél. : 33 (0)2 40 37 16 57 Fax. : 33 (0)2 40 74 74 06 Felipe.Bordeu@ec-nantes.fr Institut GeM - UMR CNRS 6183 École Centrale Nantes 1 Rue de La Noë, 44321 Nantes, FRANCE -------------------------------------