- GiNaC-list - ginac.de

non-commutative symbols (again)
by Jan 20 Feb '11

20 Feb '11

Hello, I'm afraid the logic of this is still beyond me (yes, it might be my mathematical ignorance). I created a class ncsymbol derived from basic (by copying the GinaC symbol class and overloading return_type()) Now I have the following test program --------------- #include <ginac/ginac.h> #include "ncsymbol.h" using namespace GiNaC; int main() { ncsymbol s1("s1", "s1"); symbol x("x"), y("y"); matrix M1(2,2); M1 = x, 0, y, 0; matrix M2(2,2); M2 = 0, x, x, 0; ncsymbol s2("s2"); ex nc; nc = s1 * s2; // Produces a ncmul nc = nc.subs(s1 == M1); // Produces a mul !! nc = M2 * M3; // Produces a ncmul nc = s1 * M2; // Produces a mul !! } ------------------------ 1. Why does replacing a non-commutative object with another non-commutative object result in the ncmul becoming a mul? 2. Why is the product of two (different) non-commutative objects a mul and not a ncmul? Thanks for any light, Jan

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Non-commutative symbols
by Jan 14 Feb '11

14 Feb '11

Hi, the GiNaC info documentation claims: Both symbols and user-defined functions can be specified as being non-commutative. I couldn't figure out how to create a non-commutative symbol, though, except by defining a new subclass of symbol and overloading return_type() Any hints? Thanks, Jan

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Differentiation of a function with respect to a tensor
by Bernardo Rocha 11 Feb '11

11 Feb '11

Hi everyone, I've recently discovered GiNaC and I'm really excited about its capabilities. There is one thing that I would like to know if it is able to do that I haven't found in the tutorial.pdf or in any other place that I've searched. I would like to know if, given a function \Psi=\Psi(E), like the strain energy function for the St. Venant-Kirchhoff material \Psi(E) = 0.5 * \lambda * (tr E)^2 + \mu E:E is it possible to differentiate it with respect to E, that is i would like to compute \frac{\partial \Psi}{\partial E}. If this is possible, could someone please send some examples or maybe point to which classes should I use to do that? That's all for now. Many thanks in advance. Best regards, Bernardo M. R.

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get_name() doesn't returned a name like "symbolNNN"?
by Warren Weckesser 09 Dec '10

09 Dec '10

Hi, According to the documentation (section 4.5 of the online tutorial), the following code should produce something like z.get_name() = "symbol1" but with ginac 1.5.8, I get an empty string. ----- #include <iostream> #include <ginac/ginac.h> using namespace std; using namespace GiNaC; int main() { symbol z; cout << "z.get_name() = \"" << z.get_name() << "\"" << endl; return 0; } ----- In an older version of ginac, this used to work as documented. Is this a bug, or an expected change in behavior? (Or is it just my installation that is broken?) Regards, Warren

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Bug in numer_denom?
by Ernst Moritz Hahn 23 Nov '10

23 Nov '10

Dear all, I think there is a problem with the numer_denom function with large polynomial fractions. I added "bug.txt" to the attachment, which is an input file for ginsh. Using the version of GiNaC shipped with current stable Ubuntu, I get the result "out-installed". Here, "/" is contained in numerator and denominator, which should not be the case, if I understood the functionality of numer_denom right. Using git version of GiNaC, I get "out-git.txt". Here, braces are used in numerator and denominator, which also seems strange to me. Do I understand something wrong or is this a bug? Best regards, Moritz Hahn

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Woe32 build
by Rubens Matos 08 Nov '10

08 Nov '10

Hello to everyone, I'm trying to use the Windows build of ginac, provided by Alexei Sheplyakov, but my code uses some functions that are specific from ginac 1.5 and cln 1.3, while he used ginac 1.4.4 and cln 1.2.2. I've tried to contact him, but without success. I know that the windows build is not an "official" release, but could anyone give me some help about how to build windows DLLs of ginac using the sources? I am using the Linux build perfectly, but the tool I'm developing also has a Windows version, so building these DLLs would be very important. Thank you in advance, Rubens Matos

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Re: [GiNaC-list] Woe32 build
by Rubens Matos 08 Nov '10

08 Nov '10

Thank you! I couldn't imagine that it would be so simple. I will try to follow these steps. Regards, Rubens de Souza Matos Júnior > Message: 2 > Date: Sun, 7 Nov 2010 10:01:26 +0100 > From: Kaveh Vahedipour <k.vahedipour(a)fz-juelich.de> > Subject: Re: [GiNaC-list] Woe32 build > To: GiNaC discussion list <ginac-list(a)ginac.de> > Message-ID: <6B564826-9FB9-42E6-A486-81A30AA0A7D1(a)fz-juelich.de> > Content-Type: text/plain; charset="us-ascii" > > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > Hello Rubens, > > Building the win32 is not that tough. > > I user mingw-w32 with debian. > > # ==== Set following environment f.e. for bash: > TARGET=i586-mingw32msvc > HOST=x86_64-unknown-linux-gnu > CXX=${TARGET}-g++ > CC=${TARGET}-gcc > CPPFLAGS=-I/your/choice/win32/include > CXXFLAGS="$CPPFLAGS -O3" > CFLAGS=$CXXFLAGS > LDFLAGS=-L/your/choice/win32/lib > PREFIX=/your/choice/win32 > export CC CXX CPPFLAGS CXXFLAGS CFLAGS LDFLAGS TARGET HOST > > # ==== configure and build CLN with > ./configure --target=$TARGET --host=$HOST --enable-shared --prefix=$PREFIX && make && make install > > # ==== configure GiNaC: > CLN_CFLAGS=$CPPFLAGS > CLN_LIBS="$LDFLAGS -lcln" > export CLN_CFLAGS CLN_LIBS > ./configure --target=$TARGET --host=$HOST --enable-shared --prefix=$PREFIX && make && make install > > Cheers, > Kaveh. > > On Nov 7, 2010, at 3:09 AM, Rubens Matos wrote: > >> Hello to everyone, I'm trying to use the Windows build of ginac, >> provided by Alexei Sheplyakov, but my code uses some functions that >> are specific from ginac 1.5 and cln 1.3, while he used ginac 1.4.4 and >> cln 1.2.2. I've tried to contact him, but without success. >> >> I know that the windows build is not an "official" release, but could >> anyone give me some help about how to build windows DLLs of ginac >> using the sources? >> >> I am using the Linux build perfectly, but the tool I'm developing also >> has a Windows version, so building these DLLs would be very important. >> >> Thank you in advance, >> >> Rubens Matos >> _______________________________________________ >> GiNaC-list mailing list >> GiNaC-list(a)ginac.de >> https://www.cebix.net/mailman/listinfo/ginac-list > > - --- > Kaveh Vahedipour > Institute of Neuroscience and Medicine > Medical Imaging Physics > Forschungszentrum Juelich GmbH > 52425 Juelich > Germany > Phone: +49-2461-611921 > Fax: +49-2461-611919 > E-mail: k.vahedipour(a)fz-juelich.de > Web: http://www.fz-juelich.de/inm/inm-4 > > -----BEGIN PGP SIGNATURE----- > Version: GnuPG/MacGPG2 v2.0.14 (Darwin) > > iEYEARECAAYFAkzWausACgkQFWIkraPoGKdIlgCfb8+l0QCtHxQGxoAFZkQH96Pf > 7yQAn2+cl25ocJNmyT4orEBAxAuVq6Lq > =pP2D > -----END PGP SIGNATURE----- > > ------------------------------------------------------------------------------------------------ > ------------------------------------------------------------------------------------------------ > Forschungszentrum Juelich GmbH > 52425 Juelich > Sitz der Gesellschaft: Juelich > Eingetragen im Handelsregister des Amtsgerichts Dueren Nr. HR B 3498 > Vorsitzender des Aufsichtsrats: MinDirig Dr. Karl Eugen Huthmacher > Geschaeftsfuehrung: Prof. Dr. Achim Bachem (Vorsitzender), > Dr. Ulrich Krafft (stellv. Vorsitzender), Prof. Dr.-Ing. Harald Bolt, > Prof. Dr. Sebastian M. Schmidt > ------------------------------------------------------------------------------------------------ > ------------------------------------------------------------------------------------------------ > > > ------------------------------ > > _______________________________________________ > GiNaC-list mailing list > GiNaC-list(a)ginac.de > https://www.cebix.net/mailman/listinfo/ginac-list >

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crash in cln when converting numeric to double
by Sebastian Luther 03 Nov '10

03 Nov '10

Hi, below you'll find a small test program that crashes for me. -------------------------------------------- #include <ginac/ginac.h> #include <iostream> int main(int argc, char* argv[]) { GiNaC::parser p; GiNaC::ex e = p("941480149401/1250000000000000*2^(5/91)"); GiNaC::numeric n = GiNaC::ex_to<GiNaC::numeric>(e); double x = n.to_double(); //throws the exception below return 0; } /* terminate called after throwing an instance of 'cln::notreached_exception' what(): Internal error: statement in file real/conv/cl_R_to_double.cc, line 55 has been reached!! */ -------------------------------------------- g++ test.cpp -o test -lginac -------------------------------------------- ./test -------------------------------------------- Looks like the real problem lays in cln, but I'm not sure how to reproduce it there. I tested on three systems all with cln 1.3.1. Ubutnu 10.4 (64bit) with ginac 1.5.5, gcc 4.4 Gentoo (64bit) with ginac 1.5.8, gcc-4.5 Gentoo (32bit) with ginac 1.5.5, gcc-4.4 Let me know if you need something else. Sebastian -- GMX DSL Doppel-Flat ab 19,99 €/mtl.! Jetzt auch mit gratis Notebook-Flat! http://portal.gmx.net/de/go/dsl

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pole_error when expanding power into series
by Camille Gillot 02 Nov '10

02 Nov '10

Hello, I recently came across Ginac and I found it was an excellent tool. The speed of series expansion is amazing compared to my hand-held calculator. However, ginac 1.5.8 is unable to expand expressions like : cos(x)^(sin(x)/x), even if it expands well sin(x)/x. Using ginac compiled from git some days ago, ginac-git/ginsh/ginsh [...] > series(cos(x)^(sin(x)/x),x==0,5); power::eval(): division by zero > series(((a^x+b^x)/2)^(1/x),x==0,2); power::eval(): division by zero I found out that was caused by ginac's attempt to use taylor formula in these cases (in power::series in pseries.cpp line 1129 and 1134). I give you a patch for it, that enables that kind of calculations : (in patched ginsh) > series(cos(x)^(sin(x)/x),x==0,5); 1+(-1/2)*x^2+1/8*x^4+Order(x^5) > series(((a^x+b^x)/2)^(1/x),x==0,2); (exp(1/2*log(b)+1/2*log(a)))+(-1/8*exp(1/2*log(b)+1/2*log(a))*(2*log(b)*log(a)- log(a)^2-log(b)^2))*x+Order(x^2) (or human-simplified sqrt(a*b)+(1/8*sqrt(a*b)*(log(a)-log(b))^2*x+Order(x^2) ) The exponential simplification is none of my abilities in Ginac. Bye Camille Gillot

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little optimization => lots of Memory usage
by Cristobal Navarro 22 Oct '10

22 Oct '10

Hello everybody, i've been using ginac for some months and is very optimum, but recently i've been facing a problem with the amount of memory used to store some expressions. i have a linear system of ecuations, with the size of around 8000 elements. my first approach on building the matrix was use a map<string, ex*> where each element would correspond to a row element of the matrix. and all incognints of that row would be inside the expression ex. for a 4x4 system ecuaiton, the storage would be like this <"certainKey1", ex1* > = B1*symbol2 + A1*symbol1 + D1*symbol4 <"certainKey2", ex2*> = D2*symbol4 + B2*symbol2 + C2*symbol3 <"certainKey3", ex3* > = B3*symbol2 + A3*symbol1 + D3*symbol4 + C3*symbol3 <"certainKey4", ex4*> = A4*symbol1 + B4*symbol2 + C4*symbol3 this method was using an acceptable ammount of memory, around 15% of 32GB which was pretty good. the bad side of this approach was that when building the Ginac::matrix, i had to sort the elements and search each of them on their corresponding row, additionaly some where hidden because they had coefficient "0", so i had a list of symbols and on each row i searched for them, in a sorted way using the "coeff" method that Ginac provides. But i repeat, this was slow. The point is that i decided to search for other solution, aiming on reducing the time needed to build the Ginac::Matrix. i came with the idea to use map< string, <string, ex> > mapMatrix, which is actually the matrix but sorted automatically because of the strings which are the incognits keyCode. now building the matrix is almost instant, no search needed, and all elements already sorted. however, the program is using all the RAM = 32GB when doing the 8000x8000 problem. i checked and rechecked for any memory leak, but havent found any so far, now the question = why did memory increase so much for just segmenting the expressions into separated smaller ones?? is they same ammount of terms, just in separated sub-expressions., the ex object is too expensive??

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