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That series again
by Ralf Stephan 13 Aug '04

13 Aug '04

Using the new 1.2.3, in ginsh: > series((1+x)^y,x,5); 1+Order(x^5) while > series(exp(y*log(1+x)),x,5); 1+(y)*x+(-1/2*y+1/2*y^2)*x^2+(1/3*y-1/2*y^2+1/6*y^3)*x^3+(1/24*y^4-1/4*y+11/24*y^2-1/4*y^3)*x^4+Order(x^5) My understanding is the latter is correct as it gives 1/n! the Stirling1 triangle and substituting a number for y gives binomial coefficients. Maybe any expansion of a power can be expressed by such a construction, even in the GiNaC source, so a patch would be straightforward? ralf

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GiNaC 1.2.3
by Jens Vollinga 13 Aug '04

13 Aug '04

Hi, GiNaC 1.2.3 is out and available. The changes are: - improved handling of dirac / color algebra - fixed bug in series expansion of powers - fixed and improved configuration of documentation building As always, this release can be downloaded from ftp://ftpthep.physik.uni-mainz.de/pub/GiNaC/ Enjoy, Jens

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series segv
by Ralf Stephan 12 Aug '04

12 Aug '04

This bombs in ginsh: series((1+x)^y,x,5); Thanks, ralf

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tensor manipulation....
by Matt Bellis 06 Aug '04

06 Aug '04

Hi ginac'ers, Brand new to this, so sorry if this is old hat. Couldn't find it in the archives. I want to do some simple calculations involving 4-momenta and dirac matrices. Simplest case I want to get the invariant mass of a 4-momentum. I've got this for now. #include<iostream> #include<ginac/ginac.h> using namespace std; using namespace GiNaC; int main() { symbol mu_sym("mu"); varidx mu(mu_sym, 4); symbol p1_sym("p1"); ex p1 = indexed(p1_sym, mu); symbol p2_sym("p2"); ex p2 = indexed(p2_sym, mu.toggle_variance()); ex mass = p1 * p2; cerr << mass << endl; return 0; } It looks OK, but I need to be able to enter in data for p1 and p2 so I can calculate the mass. I don't know how to do this. Anyone know? Also, right now I've got two separate expressions for the raised and lowered indices of the momentum (p1, p2). Is there an easier way to do this? Thanks in advance for any help anyone can offer. -- --------------------------- Matt Bellis Carnegie Mellon University (office) 412-268-6949 (cell) 412-310-4586 ---------------------------

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Presumably...
by Richard B. Kreckel 06 Aug '04

06 Aug '04

...the bottle of Champagne has already been emptied and the hangover is gone. This is because GiNaC release 1.2.2 has hit the FTP-server the day before yesterday. We apologize for not having sent out invitations for the release party to the public. Some of us simply couldn't afford spending tons of money on beverages for the VIPs (like we usually do). Anyways, here's the beef: * Added const_preorder_iterator and const_postorder_iterator classes (and associated methods ex::pre/postorder_begin/end()) providing tree traversal with iterators. * Fixed the LaTeX output of the varidx class. * Fixed bugs in series expansion and complex conjugation. * (p.i*p.i).get_free_indices() returns the correct result () instead of (.i). * Symbolic functions without any eval(), evalf() etc. functions now work properly. * integer_content(), content(), and primpart() now also work for polynomials with rational coefficients (calculating the LCM of coefficients' denominators). * Added method matrix::rank(). * Added function resultant(). * Added integer_content() function to ginsh. Enjoy! -richy. (Christian, I got an idea: bottle party next time!) -- Richard B. Kreckel <http://www.ginac.de/~kreckel/>

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'full' differentiation?
by Ralf Stephan 02 Aug '04

02 Aug '04

Hello, is there an easy way to get 'full' differentiation, ie, of all variables, instead of only the main variable? Example: Given symbols x,u, diff(x/u, x) would then produce (u-u'x)/u^2. At the moment, I'm abusing psi to get the effect but that is certainly not the best way. sincerely, ralf

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get_free_indices() returns wrong result
by varg＠thsun1.jinr.ru 02 Aug '04

02 Aug '04

Hello! This simple program: #include <iostream> #include <ginac/ginac.h> using namespace std; using namespace GiNaC; int main(int argc, char** argv) { symbol A("A"); symbol i_sym("i"); idx i(i_sym, 3); ex test = indexed(A, i)*indexed(A,i); exprseq free_ind = test.get_free_indices(); cout << "Free indices of expression " << test << ": "; cout << free_ind << endl; return 0; } gives: Free indices of expression (A.i)^2: (.i) but not just an empty sequence, as I expected. This patch seems to fix the inconsistency: diff -u -r GiNaC-orig/ginac/indexed.cpp GiNaC/ginac/indexed.cpp --- GiNaC-orig/ginac/indexed.cpp 2004-06-10 02:19:36.000000000 +0400 +++ GiNaC/ginac/indexed.cpp 2004-07-26 22:31:52.000000000 +0400 @@ -499,10 +499,31 @@ return free_indices; } +// checks if index is symbolic and is_exactly_a<idx> +struct is_a_symb_idx : public std::unary_function<ex, bool> { + bool operator()(const ex & e) + { + return is_exactly_a<idx>(e) && ex_to<idx>(e).is_symbolic(); + } +}; + exvector power::get_free_indices() const { - // Return free indices of basis - return basis.get_free_indices(); + exvector tmp_inds = basis.get_free_indices(); + + if (exponent.info(info_flags::even)) { + // if the exponent is an even number, then any "free" index + // of base is actually a dummy index, if it + // 1) has no variance, + // 2) is not a numeric index + exvector really_free; + remove_copy_if(tmp_inds.begin(), tmp_inds.end(), + back_inserter(really_free), is_a_symb_idx()); + return really_free; + } else { + return tmp_inds; + } + } /** Rename dummy indices in an expression.

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doc patch (overloaded user functions)
by Ralf Stephan 28 Jul '04

28 Jul '04

Hello, I would like to suggest the following patch: Regards, ralf --- ginac.texi~ Fri Jul 23 16:29:57 2004 +++ ginac.texi Wed Jul 28 11:30:44 2004 @@ -6307,6 +6307,14 @@ option which is explained in the next section. +@subsection Overloaded functions + +If you ever intend to construct functions that differ only in the number +of parameters but have the same name then the macros of the previous +section no longer can accomplish the task. In that case, we can only +advise you read the source code and how we did it in the cases of +@code{psi} and @code{zeta}. It can be found in the files @code{inifcns.h}, +(a)code{inifcns_gamma.cpp} and @code{inifcns_nstdsums.cpp}, respectively. @node Printing, Structures, Symbolic functions, Extending GiNaC @c node-name, next, previous, up

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Majordomo is dead, long live Mailman!
by Christian Bauer 18 Jul '04

18 Jul '04

Hello! The GiNaC mailing lists are now running under the Mailman mailing list software. You should have received an Email with your personal subscription password and some instructions on how to change your subscription settings and how to unsubscribe. To fend off spam, only subscribed members can post to the lists now. If you are using multiple Email addresses for posting, you can subscribe all of them, and set all except one to "nomail" on the subscription options page, so you won't get duplicate messages. The list archives have been preserved and can be accessed here: http://thep.physik.uni-mainz.de/pipermail/ginac-list/ http://thep.physik.uni-mainz.de/pipermail/ginac-devel/ Have fun, Christian -- / Physics is an algorithm \/ http://www.uni-mainz.de/~bauec002/

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doc patch
by Ralf Stephan 11 Jun '04

11 Jun '04

Hello, I thought this was missing from the documentation: --- ginac.texi.orig Mon Mar 15 18:47:17 2004 +++ ginac.texi Thu Jun 10 09:41:09 2004 @@ -4905,6 +4905,12 @@ @item @code{binomial(n, m)} @tab binomial coefficients @cindex @code{binomial()} +@item @code{bernoulli(n)} +@tab Bernoulli numbers +@cindex @code{bernoulli()} +@item @code{fibonacci(n)} +@tab Fibonacci numbers +@cindex @code{fibonacci()} @item @code{Order(x)} @tab order term function in truncated power series @cindex @code{Order()}

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