Hello Souleiman, can you stop posting HTML and not attaching irrelevant old mails?
> In my rules for the simplification of my matrix 4*4, there a lot of > expression of the type « *y11*y12==-y12*y11* », in fact the place of the* > yij *(*in the first position or in the second position, there are commuting > only if all the indice are different*) is important but i remark that for > fricas it is the same. FriCAS is one of the few systems that can use "*" both for denoting commutative and non-commutative multiplication. However, within the type Expression(Integer) "*" is meant to be commutative. > Here are my rules : « *yjk*yjl=-yjl*yjk for k ≠ l;ykj*ylj=-ylj*ykj for k ≠ > l; yjk*ylm=ylm*yjk for j ≠ l and k ≠ m*». OK. But I have the impression that this is only part of your problem. Obviously, you want to have this in connection with your logrules. For a good suggestion it would be good to have a full description of what you are trying to achieve. In particular, you seem to focus on (simplification) rules. FriCAS is different to most other CAS. One usually doesn't just enter an expression and then "simplifies" or transforms it, but rather one thinks in advance in which "domain" that expression lives. So for your "non-commutative" multiplication I would probably define a polynomial ring with the yij's as variables and a special multiplication. And then enter your data as elements of this domain. Then the "simplification" happens automatically, since your "domain" knows all about the properties of the non-commutative multiplication. In other words, you implement a non-commutative algebra and then work in that. Yes, that involves a bit of programming. If, however, you want to use such an algebra in connection with rules, it probably gets a little more involved. Ralf -- You received this message because you are subscribed to the Google Groups "FriCAS - computer algebra system" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/fricas-devel. For more options, visit https://groups.google.com/d/optout.
