From df4af1f82d60e271094846b3a4a07c33aecfa3aa Mon Sep 17 00:00:00 2001 From: Christian Bauer Date: Thu, 5 Apr 2001 20:58:36 +0000 Subject: [PATCH] documentation update --- NEWS | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/NEWS b/NEWS index a2ef2d1f..2d6b6622 100644 --- a/NEWS +++ b/NEWS @@ -12,8 +12,13 @@ This file records noteworthy changes. gamma~0 in p.mu*gamma~mu should be p.0 but is returned as 0 - using coeff(), tcoeff(), lcoeff() or collect() on elements of noncommutative products might return wrong or surprising results -* Likewise, subs() can be used to substitute functions, tensors and indexed - expressions. +* subs() no longer only substitutes symbols and indices but performs a more + general "syntactic substitution", i.e. it substitutes whole objects in sub- + expressions. You can subs((a+b)^2,a+b==3) and get 9, but subs(a+b+c,a+b==3) + doesn't do anything. + Limitations: + - substituting numerics (subs(expr, 2==4)) will not replace then in all + occurences; in general, you shouldn't substitute numerics, though * Added preliminary (re)implementations of color and clifford classes. * simplify_indexed(): contraction of symmetric and antisymmetric tensors is zero. -- 2.49.0