- GiNaC-list - ginac.de

indexed object
by Gilson Dallabona 02 Nov '07

02 Nov '07

Hi, I'm a new user of Ginac and I have found a problem. I need to define an indexed object with six indices or more. However, for an indexed object with more than four indices the compilation returns an error. A simple example is: symbol Delta("Delta"); varidx mu(symbol("mu"),4), nu(symbol("nu"),4), alpha(symbol("alpha"),4), beta(symbol("beta"),4), sigma(symbol("sigma"),4), lambda(symbol("lambda"),4); ex e = indexed(Delta,mu,nu,alpha,beta,alpha,beta); cout << e << endl; returns a compilation error like this "error: no matching function for call to 'GiNaC::indexed::indexed(GiNaC::symbol&, GiNaC::varidx&, GiNaC::varidx&, GiNaC::varidx&, GiNaC::varidx&, GiNaC::varidx&, GiNaC::varidx&)" Is there a way to define an indexed object with more than four indices in Ginac? Thanks, Gilson.

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new tinfo method makes is_a less efficient
by Diego Conti 13 Sep '07

13 Sep '07

Hi, I'm a mathematician and I find GiNaC very useful for doing calculations. Unfortunately, the new tinfo mechanism in version 1.4.0 breaks my code, and I am not sure how to fix that. Basically, what I need is an efficient version of is_a (actually, is_a<ncmul>) that does not rely on dynamic_cast. With the old tinfo method, I could simply redefine: template<> inline bool is_a<ncmul>(const basic & obj) { return (obj.tinfo()&TINFO_MASK)==TINFO_ncmul; } where TINFO_MASK is the constant 0x001fffffU, and the classes I derived from ncmul had appropriate tinfo constants. With the new method, where the tinfo_key is a pointer, the above code does not work. One obvious alternative is the following: struct tinfo_static_t <http://www.ginac.de/reference/structGiNaC_1_1tinfo__static__t.html> { const tinfo_static_t* derives_from; //NULL if derived from void, otherwise points to tinfo_static member in superclass <http://www.ginac.de/reference/structGiNaC_1_1tinfo__static__t.html> }; typedef const tinfo_static_t * tinfo_t; and then template <class T> inline bool is_a(const basic &obj) { const tinfo_static_t* tinfo=obj.tinfo(); do { if (tinfo==&T::tinfo_static) return true; tinfo = tinfo->derives_from <http://www.ginac.de/reference/structGiNaC_1_1tinfo__static__t.html>; } while (tinfo!=NULL); return false; } This appears reasonably efficient, but it will not work because, for instance, add::return_type_tinfo <http://www.ginac.de/reference/classGiNaC_1_1add.html#b2>() can return this, which can be converted to a pointer to void but not to a pointer to tinfo_static_t. I really do not understand the meaning of this choice. Can someone explain? What would I need to change in order to make the above code work? Thanks in advance Diego Conti

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Installation ginac(1.4) + cln(1.1.13) on powermac
by Hans-Jürgen Greif 11 Sep '07

11 Sep '07

Hi to all, because octave can't install symbolic package, I have tried to install ginac on powermac G4 v. 10.4.10. The ginac configure script ends with: checking for pkg-config... /sw/bin/pkg-config checking pkg-config is at least version 0.9.0... yes checking for CLN... configure: error: Package requirements (cln >= 1.1.6) were not met. Consider adjusting the PKG_CONFIG_PATH environment variable if you installed software in a non-standard prefix. Alternatively you may set the CLN_CFLAGS and CLN_LIBS environment variables to avoid the need to call pkg-config. See the pkg-config man page for more details. ________________________ I have no experience with pkg-config, so I decided to use environments variables bash shell: declare -x CLN_CFLAGS="-I/usr/local/include/cln" declare -x CLN_ LIBS="-L/usr/local/libs/ -lcln" for installed cln 1.1.13 which is definitely greater (newer) as 1.1.6. However, this does not work. Can anyone tell to me, how to set the variables above. Or can anyone give a pkg file to handle this problem? Sincerely, Hans-Jürgen Greif

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Installation ginac(1.4) +cln(1.1.3) on powermac
by Hans-Jürgen Greif 08 Sep '07

08 Sep '07

The system I use is (uname -a) Darwin alpha.local 8.10.0 Darwin Kernel Version 8.10.0: Wed May 23 16:50:59 PDT 2007; root:xnu-792.21.3~1/RELEASE_PPC Power Macintosh powerpc The config.log is attached. Regards, Hans-Jürgen Greif

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GiNaC release 1.4.0
by Jens Vollinga 31 Aug '07

31 Aug '07

Hello everybody, GiNaC 1.4.0 is out and available. The changes are: - New tinfo mechanism. - Removed rtt from class symbol. - Faster archiving by adding a map from strings to indices in the atoms vector. - Improved unarchiving: algorithms order N instead of order N^2. - Added compile function, excompiler class. - Added exset type. - Added step function to GiNaCs built-in functions. - Added is_polynomial() method. - Added real_part() and imag_part() methods. - Added matrix::is_zero_matrix() method. - Added evalm() method to pseries class. - Improved dummy index renaming. - Many improvements for class clifford. - New flag for positive symbols/numbers, added possymbol class. - Added programming examples in doc/examples *Note*: the tinfo mechanism has changed from fixed magic numbers to dynamically assigned tinfo-ids. If have written your own GiNaC classes, you need to adjust your code! As always, this release can be downloaded from http://www.ginac.de/Download.html Best wishes, Jens

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GiNaC release 1.3.8
by Jens Vollinga 28 Aug '07

28 Aug '07

Hello everybody, GiNaC 1.3.8 is out and available. The changes are: - Drop support of ginac-config and ginac.m4. Please use pkg-config instead. - atan2(y,x) branch cut correction. - Fixed bug in series expansion. - Additional transformations for mul and power. - Clifford units now honor representation labels. - Correct csrc output for idx and fderivative. - Improved handling of convergence transformationis for Li/G. - Fix compilation issues with prereleases of GCC 4.3. - info_flags::expanded added. - input_parser also accepts pow(). - texinfo.tex removed from package. As always, this release can be downloaded from http://www.ginac.de/Download.html Best wishes, Jens

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'Nice' output of GiNaC in C++ CGI
by Yigal Asnis 06 Aug '07

06 Aug '07

Hi, I'm building web site for interactive solving school math problems using GiNaC and cgicc. My question is how to output GiNaC's expressions into web-page in form of formatted formulae (image file) rather than one-row string. Thanks for your help in advance. Yigal. ____________________________________________________________________________________ Choose the right car based on your needs. Check out Yahoo! Autos new Car Finder tool. http://autos.yahoo.com/carfinder/

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dirac_slash(0) Does'nt work !!!
by J. gallardo 06 Aug '07

06 Aug '07

I'm trying to write an expression wich uses a Dirac " gamma 0 " for calculations on spin polarization projector, the line looks like: ex XAA=dirac_slash(0)* dirac_slash(k,4)*proj1* dirac_slash(E,4)* (dirac_slash(p,4)+ m * dirac_ONE()) * dirac_slash(E,4) * dirac_slash(k,4)*proj1* dirac_slash(E1,4) * (dirac_slash(p1,4)+m * dirac_ONE()); i'm not surethis is right, but I can't find other way to put a "gamma 0" in the expression... For instance I get the error: /usr/local/include/ginac/clifford.h: In function ‘int main()’: /usr/local/include/ginac/clifford.h:231: error: too few arguments to function ‘GiNaC::ex GiNaC::dirac_slash(const GiNaC::ex&, const GiNaC::ex&, unsigned char)’ QED_slasshes.cc:80: error: at this point in file what is wrong ? How I have to do it? Thanks. Jorge. -- View this message in context: http://www.nabble.com/dirac_slash%280%29-Does%27nt-work-%21%21%21-tf4167675… Sent from the Ginac - General mailing list archive at Nabble.com.

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[bug] pi example program does not report correct accuracy
by xt knight 28 Jul '07

28 Jul '07

This is a simple bug and it's reproducible on every machine. Using the pi example in libcln (./examples), type this: pi 5 3.1415927 is not 5 digits. pi 1 3.1416 is not 1 digit. https://bugs.launchpad.net/debian/+source/cln/+bug/128851 This bug reporter also mentions that it rounds the last number and that's not documented anywhere. Thank you for your time, xtknight

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Re: GiNaC-list Digest, Vol 29, Issue 1
by Jan Bos 25 Jul '07

25 Jul '07

Dear Richard, Thanks for the prompt reply. I'm no expert and not aware of LIA-3. Maybe you could give me a reference as where to obtain it? The reason I posted the question is that since GiNaC is embedded in C++ (beautiful concept by the way) it seems odd to have different definitions for the case at hand. Of course I can't oversee the consequences of a change, it would be convenient to code decisions based on the argument in a uniform way though. Best regards Jan Bos On Sun, 2007-07-22 at 12:00 +0200, ginac-list-request(a)ginac.de wrote: > Send GiNaC-list mailing list submissions to > ginac-list(a)ginac.de > > To subscribe or unsubscribe via the World Wide Web, visit > https://www.cebix.net/mailman/listinfo/ginac-list > or, via email, send a message with subject or body 'help' to > ginac-list-request(a)ginac.de > > You can reach the person managing the list at > ginac-list-owner(a)ginac.de > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of GiNaC-list digest..." > > > Today's Topics: > > 1. atan2(0,-4) = -Pi? (Jan Bos) > 2. Re: atan2(0,-4) = -Pi? (Richard B. Kreckel) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Sat, 21 Jul 2007 21:24:57 +0200 > From: Jan Bos <jb68(a)xs4all.nl> > Subject: [GiNaC-list] atan2(0,-4) = -Pi? > To: ginac-list(a)ginac.de > Message-ID: <1185045897.9600.20.camel@jbos1> > Content-Type: text/plain > > Dear All, > > Is there a reason for GiNaC (or ginsh) to evaluate > atan2(0,-4) as -Pi instead of +Pi the definition used by for instance > C/C++? Looking at the code, inifcns_trans.cpp last shown case below, > explicitly states it should. Or can I expect it to be changed in the > future? > > static ex atan2_eval(const ex & y, const ex & x) > { > if (y.info(info_flags::numeric) && x.info(info_flags::numeric)) { > > if (y.is_zero()) { > > // atan(0, 0) -> 0 > if (x.is_zero()) > return _ex0; > > // atan(0, x), x real and positive -> 0 > if (x.info(info_flags::positive)) > return _ex0; > > // atan(0, x), x real and negative -> -Pi > if (x.info(info_flags::negative)) > return _ex_1*Pi; > } > > ... > > The code fragment is from version 1.3.7 > > best regards > > Jan Bos > > > > > > ------------------------------ > > Message: 2 > Date: Sun, 22 Jul 2007 01:16:38 +0200 > From: "Richard B. Kreckel" <kreckel(a)ginac.de> > Subject: Re: [GiNaC-list] atan2(0,-4) = -Pi? > To: GiNaC discussion list <ginac-list(a)ginac.de> > Message-ID: <46A293D6.9040301(a)ginac.de> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > > Dear Jan, > > Jan Bos wrote: > > Is there a reason for GiNaC (or ginsh) to evaluate > > atan2(0,-4) as -Pi instead of +Pi the definition used by for instance > > C/C++? Looking at the code, inifcns_trans.cpp last shown case below, > > explicitly states it should. Or can I expect it to be changed in the > > future? > > > > static ex atan2_eval(const ex & y, const ex & x) > > { > > if (y.info(info_flags::numeric) && x.info(info_flags::numeric)) { > > > > if (y.is_zero()) { > > > > // atan(0, 0) -> 0 > > if (x.is_zero()) > > return _ex0; > > > > // atan(0, x), x real and positive -> 0 > > if (x.info(info_flags::positive)) > > return _ex0; > > > > // atan(0, x), x real and negative -> -Pi > > if (x.info(info_flags::negative)) > > return _ex_1*Pi; > > } > > > > I don't suppose anybody lightly intends to change such definitions. :) > > Well, I looked in my notes and didn't find anything motivating that > choice for atan2. > > I recall that back when I wrote this, CLTL 2nd edition provided guidance > when choosing branch cuts of single-argument functions in the complex > domain. And later at some point I realized that the C99 standard agrees > with CLTL for all single-argument functions. (That appeared to be too > good to be true, but it is true.) Nobody was aware of LIA-3 at that time > but I'm quite sure that all of GiNaC's single-argument functions agree > with LIA-3, simply because they agree with C99. > > Our two-argument function atan2, however, may never have been checked > against any standard. I just did that with C99 and CLTL, and they both > specify atan2(0,-4) to be +Pi, indeed. Maybe, we ought to change this? > Before we do so: What does LIA-3 say? > > Our choice may be bad but I frankly admit that I don't know why +Pi is > any better than -Pi, or a more symmetric choice a la Mathematica like > atan2(0,x>0)=Pi/2, atan2(0,x<0)=-Pi/2, or 0 for all x. Can you explain > that choice? > > Cheers > -richy. > > PS: In any case, this is a good lesson how not to write comments, sigh. > -- > Richard B. Kreckel > <http://www.ginac.de/~kreckel/> > > > ------------------------------ > > _______________________________________________ > GiNaC-list mailing list > GiNaC-list(a)ginac.de > https://www.cebix.net/mailman/listinfo/ginac-list > > > End of GiNaC-list Digest, Vol 29, Issue 1 > ***************************************** >

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