April 2001 - GiNaC-list

Version 0.8.2...
by Richard B. Kreckel 24 Apr '01

24 Apr '01

...claims to feature the following new stuff: * degree(), ldegree(), coeff(), lcoeff(), tcoeff() and collect() work with non-symbols as the second argument in ginsh. * the argument to collect() can be a list of objects in which case the result is either a recursively collected polynomial, or a polynomial in a distributed form with terms like coeff*x1^e1*...*xn^en, as specified by the second argument to collect(). * Several bugfixes (including a nasty memory leak in .normal()). * class matrix: solve() doesn't call algorithms redundantly any more and inverse() falls back to solve() which works in more general cases. Enjoy -richy. -- Richard Kreckel <Richard.Kreckel(a)Uni-Mainz.DE> <http://wwwthep.physik.uni-mainz.de/~kreckel/> - To UNSUBSCRIBE, email to ginac-list(a)ginac.de with a subject of "unsubscribe".

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The easter release 0.8.1 has finally landed.
by Richard B. Kreckel 16 Apr '01

16 Apr '01

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. 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, 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 -richy. -- Richard Kreckel <Richard.Kreckel(a)Uni-Mainz.DE> <http://wwwthep.physik.uni-mainz.de/~kreckel/> - To UNSUBSCRIBE, email to ginac-list(a)ginac.de with a subject of "unsubscribe".

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collect() eats fractions
by Pearu Peterson 12 Apr '01

12 Apr '01

Hi! In ginsh (ginac V0.8.0): > x/(1+x); (1+x)^(-1)*x > collect(x/(1+x),x); 0 <----??? > collect(1+x/(1+x),x); 1 <----??? > collect(x+x/(1+x),x); (1+(1+x)^(-1))*x Is this GiNaC bug or feature? Pearu - To UNSUBSCRIBE, email to ginac-list(a)ginac.de with a subject of "unsubscribe".

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Is ncmul depreciated?
by Pearu Peterson 09 Apr '01

09 Apr '01

Hi! I have noticed that ncmul(2,a,3) results mul(a,6). Why is this type change ncmul -> mul? Will ncmul be depreciated in future? Pearu - To UNSUBSCRIBE, email to ginac-list(a)ginac.de with a subject of "unsubscribe".

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