degree(), ldegree(), coeff(), lcoeff(), tcoeff() and collect() can now

[ginac.git] / NEWS

diff --git a/NEWS b/NEWS
index 8c11cffc96ef9a4b3ffb9fbf601c3599f491374a..d68d427b2fbd3044b52af538999ed394ca631e62 100644 (file)
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 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 and indexed expressions as well, so you can use
+  it to collect by powers of Pi or find the coefficient of gamma~0.
+  Limitations:
+   - it only works with symbols, constants 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 the functions on elements of noncommutative products might
+     return wrong or surprising results
+* Added preliminary (re)implementations of color and clifford classes.
+* simplify_indexed(): contraction of symmetric and antisymmetric tensors
+  is zero.
+* 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
   indices with variance. There are predefined delta, epsilon and metric
   tensors, and a function simplify_indexed() that performs canonicalization
-  and dummy index summations.
+  and dummy index summations. Matrix objects can be indexed for doing simple
+  linear algebra.
 * Added an option "expand_indexed" to expand() to perform expansion of
   indexed objects like (a+b).i -> a.i + b.i
 * Renamed get_indices() to get_free_indices(), which no longer returns
   dummy indices and checks the consistency of indices in sums.
 * 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().
 * 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.
 
 0.7.3 (28 February 2001)
 * Several bugfixes and minor performance tunings.