I'm trying to create a question with linear equation system using STACK / Maxima. My system is under-determined, so, Maxima produces variables like %r1 and %r2 in the output. I want to change their names to, for example, C1 and C2. Maxima documentation recommends to use variable %rnum_list for doing so. But when I try to use it, Stack returns an error:
% found in expression xot:subst(C1,%rnum_list,x).
So, how can I use %rnum_list in Stack. (Direct access to %r1 and %r2 returns the same error.)