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.
+ 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 and indexed expressions;
+ - 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 the functions on elements of noncommutative products might
- return wrong or surprising results
+ - 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)