July 2005 - GiNaC-devel

Patch for products of dummy summations
by Vladimir Kisil 12 Nov '05

12 Nov '05

Here is the patch which was described in my previous message (Fri May 13 17:27:25 CEST 2005). -- Vladimir V. Kisil email: kisilv(a)maths.leeds.ac.uk -- www: http://maths.leeds.ac.uk/~kisilv/

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TINFO policy (WAS: [GiNaC-devel] Another clifford patch)
by Vladimir V. Kisil 27 Jul '05

27 Jul '05

>>>>> "RK" == Richard B Kreckel <kreckel(a)ginac.de> writes: RK> This sounds like a helluvagood idea. The only thing I'm worried RK> about is I am also thinking about some kind of policy to choose a right TINFO for new homemade GiNaC classes. It will be good to avoid possible clashes in the case of all such examples collected in one place. Best, -- Vladimir V. Kisil email: kisilv(a)maths.leeds.ac.uk -- www: http://maths.leeds.ac.uk/~kisilv/

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Another clifford patch
by Vladimir Kisil 23 Jul '05

23 Jul '05

Dear All, Here is another patch for Clifford part of GiNaC which contains mainly four components: 1. Some housekeeping alteration of code. 2. Previously GiNaC method is_equal() did not take in account representation labels, i.e. a call dirac_gamma(mu).is_equal(dirac_gamma(mu, 1)) returned true. This leads to miscalculations since for example (dirac_gamma(mu) *(dirac_gamma(mu, 1)).to_rational(L) returned something like pow(symbol7, 2) instead of symbol7*symbol8. I fixed it through an "inclusion" of representation_label as op(2) for dirac_gammas. A fake alteration of let_op(2) is also made. This may not look somewhat trick but I cannot find a better solutions. By the way, does the same problem affects color.cpp? 3. Since metric member variable of the clifford class can contains symbolic entries I add susb() methods which can access metric as well. 4. I add a new member variable commutator sign to clifford class. It is used in the transformations for two clifford instances X and Y as follows: X*Y = commutator_sign*Y*X + 2*metric(X, Y) commutator_sign is an int type and for Clifford algebras is equal to -1. Such an addition with only two lines altered in canonicalize_clifford() allows to derive from clifford class subclasses for Lie algebras (commutator_sign = 1, an demo example is attached) and general algebras defined through commutation identities (e.g. q-deformed algebras can be defined for commutator_sign =0 and a proper construction of the metric). The bubble-sorting realisation of canonicalize_clifford() was initially good for simply anticommuting Dirac gammas. However since the clifford class was very generalised it becomes rather inefficient for high powers of elements and a proper modification is in the "to-do" list. Will it be worth to develop the included Lie algebra subclass into the proper part of GiNaC? Such an addition do break a binary compatibility however this only happens for low level constructors which was recommended to avoid in the user programs. Best wishes, Vladimir -- Vladimir V. Kisil email: kisilv(a)maths.leeds.ac.uk -- www: http://maths.leeds.ac.uk/~kisilv/

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GiNaC 1.3.2 release
by Jens Vollinga 11 Jul '05

11 Jul '05

Hi, GiNaC 1.3.2 is out and available. The changes are: - GCD avoids to produce expanded expressions. - Fixed bug in expanding expressions containing dummy indices. - Fixed static initialization order bug. - collect_common_factors now works with powers. - Modernized configuration scripts. Thanks to all the contributers, especially C.Dams, V.Kisil and A.Sheplyakov. As always, this release can be downloaded from ftp://ftpthep.physik.uni-mainz.de/pub/GiNaC/ Enjoy, Jens Vollinga

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