added basic::get_precedence()

[ginac.git] / NEWS

diff --git a/NEWS b/NEWS
index 3234725c22f773cf82117906b689129e9efeef39..ddc96b3bc8d57115ea232433bae6148509bf932f 100644 (file)
--- a/NEWS
+++ b/NEWS
@@ -1,6 +1,35 @@
 This file records noteworthy changes.
 
-0.8.0 (<date>)
+0.8.1 (<date>)
+* degree(), ldegree(), coeff(), lcoeff(), tcoeff() and collect() can now
+  be used with constants, functions and indexed expressions as well, so you
+  can use it to collect by powers of Pi or sin(x), or to find the coefficient
+  of gamma~0.
+  Limitations:
+   - it only works with symbols, constants, functions and indexed expressions;
+     trying to find the coefficient of, e.g., "x^2" or "x+y" won't work
+   - it does not know about dummy index summations; the coefficient of
+     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
+* 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.
+* Replaced the various print*() member functions by a single print() that
+  takes a print_context object that determines the output formatting. This
+  should make it easier to add more output types.
+* Added functions to retrieve the properties stored in archive objects
+  outside of unarchive() (for printing or debugging purposes).
+* Some bugfixes (indexed objects, archive writing).
+
+0.8.0 (24 March 2001)
 * Complete revamp of indexed objects. Instead of multiple classes for
   indexed things and their indices there is now only one "indexed" class
   and two types of indices: "idx" for simple indices and "varidx" for
@@ -15,7 +44,7 @@ This file records noteworthy changes.
 * sqrfree() factorization fixed and improved syntactically.
 * subs() works on matrices.
 * Matrices can be constructed from flat list of elements; diagonal matrices
-  can be constructed from list of diagonal elements with diag_matrix()
+  can be constructed from list of diagonal elements with diag_matrix().
 * Fixed memory leak in expand().
 * Operator% for objects of class ncmul has gone.  Use operator* now for that
   case too, which is much more natural.