The easter release 0.8.1 has finally landed.

Richard B. Kreckel kreckel at
Mon Apr 16 18:32:37 CEST 2001

Hello all,

Now let's quickly start finding all those easter eggs that Christian has
promised to stuff into the code!

This is what's documented in the NEWS file:

* 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.
   - 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*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.
   - 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, such as LaTeX output,
  which is based on work by Stefan Weinzierl.
* Added functions to retrieve the properties stored in archive objects
  outside of unarchive() (for printing or debugging purposes).
* Some bugfixes (indexed objects, archive writing).
* .collect() on non-polynomials is now algebraically correct.

Happy hacking
Richard Kreckel
<Richard.Kreckel at Uni-Mainz.DE>

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