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Re: [GiNaC-list] A strange behaviour while implementing archive in auser-defined class
by Feng Feng 20 Dec '21

20 Dec '21

Thanks very much for the patch! And again thanks a lot for the suggestions for Symbol::calchash, that is really what I am looking for! Best regards! Feng 在 2021年12月20日 16:57，Oleg Finkelshteyn<olegfink(a)gmail.com> 写道： i suspect this is actually due to a typo in relational::compare_same_type. (basic reality check: pathologic (e.g. constant) hash functions should lead to degraded performance, not different results) diff --git a/ginac/relational.cpp b/ginac/relational.cpp index 599a2635..dbc541a3 100644 --- a/ginac/relational.cpp +++ b/ginac/relational.cpp @@ -223,8 +223,8 @@ int relational::compare_same_type(const basic & other) const return (o < oth.o) ? -1 : 1; break; } - const int lcmpval = lh.compare(oth.rh); - return (lcmpval!=0) ? lcmpval : rh.compare(oth.lh); + const int lcmpval = lh.compare(oth.lh); + return (lcmpval!=0) ? lcmpval : rh.compare(oth.rh); } attached is also a shorter test along the same lines as Feng's. it prints the result of comparing two symbol==0 expressions to each other both ways. without the patch, the output is -1 -1 (which is inconsistent), and with the patch it's -1 1. a hash collision is needed to elicit this bug because basic::compare returns early without calling compare_same_type if hashes differ. Feng: regardless of this bug, i think you'll want something like following: unsigned Symbol::calchash() const { hashvalue = get_symbol(get_name()).gethash(); setflag(status_flags::hash_calculated); return hashvalue; } thanks On Sat, 18 Dec 2021, at 11:10, Vladimir V. Kisil wrote: >>>>>> On Sat, 18 Dec 2021 16:22:22 +0800, Feng Feng <f.feng(a)outlook.com> said: > FF> I got a strange behaviour while implementing the archive in > FF> user-defined class, to make the behaviour more explicitly, let > > If you will delete the method Symbol::calchash() from your class you > will get the expected behaviour. > -- > Vladimir V. Kisil http://www.maths.leeds.ac.uk/~kisilv/ > Book: Geometry of Mobius Maps https://doi.org/10.1142/p835 > Soft: Geometry of cycles http://moebinv.sourceforge.net/ > Jupyter notebooks: https://github.com/vvkisil?tab=repositories >>>>>> On Sat, 18 Dec 2021 16:22:22 +0800, Feng Feng <f.feng(a)outlook.com> said: > > FF> Dear all, > > > FF> I got a strange behaviour while implementing the archive in > FF> user-defined class, to make the behaviour more explicitly, let > FF> me post the C++ code here: > > > FF> #include <ginac/ginac.h> #include <fstream> > > > FF> using namespace GiNaC; using namespace std; > > > FF> class Symbol : public symbol { > FF> GINAC_DECLARE_REGISTERED_CLASS(Symbol, symbol) public: > FF> Symbol(const string &s); void archive(archive_node & n) const > FF> override; void read_archive(const archive_node& n, lst& sym_lst) > FF> override; unsigned calchash() const override; }; > FF> GINAC_DECLARE_UNARCHIVER(Symbol); > > > FF> GINAC_IMPLEMENT_REGISTERED_CLASS(Symbol, symbol) > FF> GINAC_BIND_UNARCHIVER(Symbol); > > > FF> const symbol & get_symbol(const string & s) { static map<string, > FF> symbol> dict; if (dict.find(s) == dict.end()) dict[s] = > FF> symbol(s); return dict[s]; } > > > FF> Symbol::Symbol() { } Symbol::Symbol(const string &s) : > FF> symbol(get_symbol(s)) { } int Symbol::compare_same_type(const > FF> basic &other) const { const Symbol &o = static_cast<const Symbol > FF> &>(other); int ret = get_name().compare(o.get_name()); > FF> if(ret==0) return 0; else if(ret<0) return -1; else return 1; } > > FF> void Symbol::archive(archive_node & n) const { > FF> inherited::archive(n); } > > FF> void Symbol::read_archive(const archive_node& n, lst& sym_lst) { > FF> inherited::read_archive(n, sym_lst); *this = Symbol(get_name()); > FF> } > > > FF> unsigned Symbol::calchash() const { static auto hash = > FF> symbol("_").gethash(); return hash; } > > > FF> int main() { Symbol k1("k1"), k2("k2"); auto garfn = "tmp.gar"; > > FF> { archive ar; ex val = lst{ k1*k1, k2*k2 }; > FF> ar.archive_ex(val, "key"); ofstream out(garfn); out << ar; > FF> out.close(); cout << "writed: " << val << endl; } { archive ar; > FF> ifstream in(garfn); in >> ar; in.close(); auto val = > FF> ar.unarchive_ex(lst{}, "key"); cout << "read: " << val << endl; > FF> } // console output is // writed: {k1^2,k2^2} // read: > FF> {k1^2,k2^2} > > FF> { archive ar; ex val = lst{ k1*k1==0, k2*k2==0 }; > FF> ar.archive_ex(val, "key"); ofstream out(garfn); out << ar; > FF> out.close(); cout << "writed: " << val << endl; } { archive ar; > FF> ifstream in(garfn); in >> ar; in.close(); auto val = > FF> ar.unarchive_ex(lst{}, "key"); cout << "read: " << val << endl; > FF> } // console output is // writed: {k1^2==0,k2^2==0} // read: > FF> {k1^2==0,k1^2==0} // Note that the last line above, both items > FF> are the same: k1^2==0 > > FF> return 0; } > > > FF> Here I want to introduce a class Symbol, when one defines Symbol > FF> a(“a”), b(“a”);, then a and b will be the same or equal, so I > FF> override the method compare_same_type. > > > > > FF> The last console output seems very strange to me, the both items > FF> are the same, while the expected result is "read: > FF> {k1^2==0,k2^2==0}”. > > > FF> Thanks very much! > > > FF> Best regards! Feng > > FF> ---------------------------------------------------- > FF> Alternatives: > > FF> ---------------------------------------------------- > FF> _______________________________________________ GiNaC-list > FF> mailing list GiNaC-list(a)ginac.de > FF> https://www.ginac.de/mailman/listinfo/ginac-list > _______________________________________________ > GiNaC-list mailing list > GiNaC-list(a)ginac.de > https://www.ginac.de/mailman/listinfo/ginac-list

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A strange behaviour while implementing archive in a user-defined class
by Feng Feng 20 Dec '21

20 Dec '21

Dear all, I got a strange behaviour while implementing the archive in user-defined class, to make the behaviour more explicitly, let me post the C++ code here: #include <ginac/ginac.h> #include <fstream> using namespace GiNaC; using namespace std; class Symbol : public symbol { GINAC_DECLARE_REGISTERED_CLASS(Symbol, symbol) public: Symbol(const string &s); void archive(archive_node & n) const override; void read_archive(const archive_node& n, lst& sym_lst) override; unsigned calchash() const override; }; GINAC_DECLARE_UNARCHIVER(Symbol); GINAC_IMPLEMENT_REGISTERED_CLASS(Symbol, symbol) GINAC_BIND_UNARCHIVER(Symbol); const symbol & get_symbol(const string & s) { static map<string, symbol> dict; if (dict.find(s) == dict.end()) dict[s] = symbol(s); return dict[s]; } Symbol::Symbol() { } Symbol::Symbol(const string &s) : symbol(get_symbol(s)) { } int Symbol::compare_same_type(const basic &other) const { const Symbol &o = static_cast<const Symbol &>(other); int ret = get_name().compare(o.get_name()); if(ret==0) return 0; else if(ret<0) return -1; else return 1; } void Symbol::archive(archive_node & n) const { inherited::archive(n); } void Symbol::read_archive(const archive_node& n, lst& sym_lst) { inherited::read_archive(n, sym_lst); *this = Symbol(get_name()); } unsigned Symbol::calchash() const { static auto hash = symbol("_").gethash(); return hash; } int main() { Symbol k1("k1"), k2("k2"); auto garfn = "tmp.gar"; { archive ar; ex val = lst{ k1*k1, k2*k2 }; ar.archive_ex(val, "key"); ofstream out(garfn); out << ar; out.close(); cout << "writed: " << val << endl; } { archive ar; ifstream in(garfn); in >> ar; in.close(); auto val = ar.unarchive_ex(lst{}, "key"); cout << "read: " << val << endl; } // console output is // writed: {k1^2,k2^2} // read: {k1^2,k2^2} { archive ar; ex val = lst{ k1*k1==0, k2*k2==0 }; ar.archive_ex(val, "key"); ofstream out(garfn); out << ar; out.close(); cout << "writed: " << val << endl; } { archive ar; ifstream in(garfn); in >> ar; in.close(); auto val = ar.unarchive_ex(lst{}, "key"); cout << "read: " << val << endl; } // console output is // writed: {k1^2==0,k2^2==0} // read: {k1^2==0,k1^2==0} // Note that the last line above, both items are the same: k1^2==0 return 0; } Here I want to introduce a class Symbol, when one defines Symbol a(“a”), b(“a”);, then a and b will be the same or equal, so I override the method compare_same_type. The last console output seems very strange to me, the both items are the same, while the expected result is "read: {k1^2==0,k2^2==0}”. Thanks very much! Best regards! Feng

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Re: [GiNaC-list] A strange behaviour while implementing archive in auser-defined class
by Feng Feng 18 Dec '21

18 Dec '21

Dear Vladimir, Thanks very much for the quick reply! Indeed, when I remove the calchash method, I get the expected result. So when writting to an archive, GiNaC will use the hash internally, and I still have a question, why does the first console output give the result: "read: {k1^2,k2^2}”? Thanks again! Best regards! Feng 在 2021年12月18日 19:10，Vladimir V. Kisil<V.Kisil(a)leeds.ac.uk> 写道： >>>>> On Sat, 18 Dec 2021 16:22:22 +0800, Feng Feng <f.feng(a)outlook.com> said: FF> I got a strange behaviour while implementing the archive in FF> user-defined class, to make the behaviour more explicitly, let If you will delete the method Symbol::calchash() from your class you will get the expected behaviour. -- Vladimir V. Kisil http://www.maths.leeds.ac.uk/~kisilv/ Book: Geometry of Mobius Maps https://doi.org/10.1142/p835 Soft: Geometry of cycles http://moebinv.sourceforge.net/ Jupyter notebooks: https://github.com/vvkisil?tab=repositories >>>>> On Sat, 18 Dec 2021 16:22:22 +0800, Feng Feng <f.feng(a)outlook.com> said: FF> Dear all, FF> I got a strange behaviour while implementing the archive in FF> user-defined class, to make the behaviour more explicitly, let FF> me post the C++ code here: FF> #include <ginac/ginac.h> #include <fstream> FF> using namespace GiNaC; using namespace std; FF> class Symbol : public symbol { FF> GINAC_DECLARE_REGISTERED_CLASS(Symbol, symbol) public: FF> Symbol(const string &s); void archive(archive_node & n) const FF> override; void read_archive(const archive_node& n, lst& sym_lst) FF> override; unsigned calchash() const override; }; FF> GINAC_DECLARE_UNARCHIVER(Symbol); FF> GINAC_IMPLEMENT_REGISTERED_CLASS(Symbol, symbol) FF> GINAC_BIND_UNARCHIVER(Symbol); FF> const symbol & get_symbol(const string & s) { static map<string, FF> symbol> dict; if (dict.find(s) == dict.end()) dict[s] = FF> symbol(s); return dict[s]; } FF> Symbol::Symbol() { } Symbol::Symbol(const string &s) : FF> symbol(get_symbol(s)) { } int Symbol::compare_same_type(const FF> basic &other) const { const Symbol &o = static_cast<const Symbol FF> &>(other); int ret = get_name().compare(o.get_name()); FF> if(ret==0) return 0; else if(ret<0) return -1; else return 1; } FF> void Symbol::archive(archive_node & n) const { FF> inherited::archive(n); } FF> void Symbol::read_archive(const archive_node& n, lst& sym_lst) { FF> inherited::read_archive(n, sym_lst); *this = Symbol(get_name()); FF> } FF> unsigned Symbol::calchash() const { static auto hash = FF> symbol("_").gethash(); return hash; } FF> int main() { Symbol k1("k1"), k2("k2"); auto garfn = "tmp.gar"; FF> { archive ar; ex val = lst{ k1*k1, k2*k2 }; FF> ar.archive_ex(val, "key"); ofstream out(garfn); out << ar; FF> out.close(); cout << "writed: " << val << endl; } { archive ar; FF> ifstream in(garfn); in >> ar; in.close(); auto val = FF> ar.unarchive_ex(lst{}, "key"); cout << "read: " << val << endl; FF> } // console output is // writed: {k1^2,k2^2} // read: FF> {k1^2,k2^2} FF> { archive ar; ex val = lst{ k1*k1==0, k2*k2==0 }; FF> ar.archive_ex(val, "key"); ofstream out(garfn); out << ar; FF> out.close(); cout << "writed: " << val << endl; } { archive ar; FF> ifstream in(garfn); in >> ar; in.close(); auto val = FF> ar.unarchive_ex(lst{}, "key"); cout << "read: " << val << endl; FF> } // console output is // writed: {k1^2==0,k2^2==0} // read: FF> {k1^2==0,k1^2==0} // Note that the last line above, both items FF> are the same: k1^2==0 FF> return 0; } FF> Here I want to introduce a class Symbol, when one defines Symbol FF> a(“a”), b(“a”);, then a and b will be the same or equal, so I FF> override the method compare_same_type. FF> The last console output seems very strange to me, the both items FF> are the same, while the expected result is "read: FF> {k1^2==0,k2^2==0}”. FF> Thanks very much! FF> Best regards! Feng FF> ---------------------------------------------------- FF> Alternatives: FF> ---------------------------------------------------- FF> _______________________________________________ GiNaC-list FF> mailing list GiNaC-list(a)ginac.de FF> https://www.ginac.de/mailman/listinfo/ginac-list

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Substitution and re-evaluation
by Gregor Kälin 10 Nov '21

10 Nov '21

Hi, I'm extending GiNaC by some new classes and ran into a problem with subs and eval. My class, representing an integral, inherits from basic and is essentially a container class containing several ex's itself. The subs method, inherited from basic, works as expected for the substitution step, but does not re-evaluate the expression (i.e. the eval function of my class is not called after the substitution happened). The tutorial states "All GiNaC methods that transform expressions, like subs() or normal(), automatically re-evaluate their results." and, hence, I would expect that the default subs method of the basic class calls eval somewhere in the process. Is this a bug in basic::subs or am I supposed to take care of a re-evaluation of my custom classes myself (i.e. essentially overriding subs and calling eval explicitly in the process)? Looking into the source code (I'm on commit 9197695fc, ginac version 1.8.1-1) I'd expect a call to eval on line 628 of basic.cpp after all operands have been substituted, and before subs_one_level is called. Best, Gregor

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GiNaC on the web
by Dani Biró 03 Nov '21

03 Nov '21

Hey GiNaC people! First of all, thank you for this great library! I'm working on a web-based interface for GiNaC as a hobby project and I wanted to share it with you. You can try a demo frontend here: https://daninet.github.io/ginac-wasm/ Source code: https://github.com/Daninet/ginac-wasm There is no operator overloading in JavaScript, so I had to implement functions like add(), mul() for the different operations. The GiNaC commands are batched for faster processing because WASM <=> JavaScript calls are too expensive. The demo frontend includes a PEG-based parser written in JavaScript, but the embedded parser is also exposed through the parse() function. At this moment, the JavaScript/TypeScript API looks like this: const GiNaC = await initGiNaC('./dist/ginac.wasm'); const g = getFactory(); GiNaC(g.mul(g.numeric('2'), g.pow(g.symbol('x'), g.numeric('2')))); GiNaC(g.series(g.atan(g.symbol('x')), g.symbol('x'), g.numeric('5'))); On my computer, the native ginsh is about 10x faster in estimating Pi with Machin’s formula compared to my WebAssembly port. That's because of the expensive C++ exception mocks generated by Emscripten, which compensate for the lack of native browser support for exceptions in WebAssembly. I estimate that the performance gap can be brought down to about 1/2 of native performance once the native exception instructions are getting wildly available in browsers. I plan to publish it on NPM (the JavaScript package library) when I manage to stabilize the API and implement the remaining features. What do you think? Do you have any suggestions or ideas? Best regards, Dani Biró

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custom print function for GiNaC::add and GiNaC::mul for deterministic printing
by Diddens, Christian (UT-TNW) 12 Oct '21

12 Oct '21

Dear GiNaC guys, first of all: Thanks once more for your powerful library! I have written a neat C code generation for the just-in-time compilation of arbitrary multiphysics finite element equations. The equations are defined in python, can be coupled and combined, and are finally monolithically solved via the library oomph-lib. While code generation is fast, the compilation of the generated code takes some time (~10 seconds for complicated couplings of Navier- Stokes, advection-diffusion, Marangoni flow, mesh node positions for ALE methods, etc.) Now, if the code generation was deterministic, I could check whether the same code has already been compiled in a previous run and skip the compilation in that case. I could also use the tool "ccache" for this. As proposed in the manual, I therefore wanted to write my own print implementation and make sure that in particular "add" and "mul" are written in an e.g. lexiographical order. However, it is a bit problematic since the properties "epvector seq" and "ex overall_coeff" from the class "expairseq" are protected without any public getter functions. Of course, I could iterate over the "::op(index)", but this would convert each "expair" first in an "ex" and I think the "expair" together with the "overall_coeff" is definitely the better way to go. So is there any neat way to access there properties from outside of the class? I understand your decision for using hashes and do not focus on a determinstic order, but in my case, it would definitely help to same some redundant JIT compilation time. Thanks for any help, you are doing a perfect job with GiNaC. Best regards, Christian

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GiNaC 1.8.1 released
by Richard B. Kreckel 09 Aug '21

09 Aug '21

Hi, GiNaC 1.8.1 has just been tagged. Here's what's new: * Add method relational::canonical() and improve conversion of relational to Boolean (it now works on many simple symbolic cases). * Improve normalization of negative exponents. * Fix indexing multiply referenced objects with ex::operator[]. * Make functions evalf() their arguments before doing own evalf(). * Fix bugs in H_evalf() and in evaluation of iterated integrals. * Several portability improvements and compiler warning fixes. If you aren't vaccinated, consider getting, and keep hacking! -richy. -- Richard B. Kreckel <https://in.terlu.de/~kreckel/>

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Cross-compiling on Linux for Windows via x86_64-w64-mingw32-g++
by c.diddens＠utwente.nl 28 Jul '21

28 Jul '21

Dear all, first of all, I want to thank you all for this very nice piece of software. I am currently developing a Python package to wrap the finite element library oomph-lib in Python. GiNaC is required here to generate C code which is compiled on the fly to quickly assemble the weak forms which are defined in Python. In some sense, this is similar to the finite element library FEniCS, which also uses GiNaC, but oomph-lib provides better capabilities for multi-physics and ALE methods. My Python code works perfect in Linux, but as a long time goal, I also want to produce Python Wheels for Windows. However, I have a hard time to cross-compile GiNaC and CLN for Windows (64 bit). Does anyone has some experience with that? I am aware of the precompiled Windows binary, but they seem to be a bit out of date... I am grateful for any input. Best regards, Christian

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Question
by Aimad Chabounia 22 Jul '21

22 Jul '21

Hello, I am currently doing an internship and we used GiNaC in our project to simplify expressions. my question is how I can generate a balanced expression tree from a ginac expression ?? (now I create expressions in form of a binary expression tree) Thanks and regards, Aimad

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Parse error involving factorial symbol
by Roberto Bagnara 15 May '21

15 May '21

Hi there. I am reviving some 10-years old software that is based on GiNaC. When I started the work I was pessimistic, given so much time has passed. But now the thing compiles again. The problem is that I cannot parse the test-suite that was used for validation. I get: on line 392: parse error: GiNaC: parse error at line 0, column 0: expected ')' or ',' in argument list, got: "!" [GiNaC::ex GiNaC::parser::parse_identifier_expr()(parser/parser.cpp:88)] I guess something has changed in the parser, or maybe my reviving effort introduced a bug. Line 392 is the last one in this block: y (n+3)! factorial(3+n) factorial(3+n) factorial(n)*(3+n)*(1+n)*(2+n) factorial(3+n) factorial(3+n) This is the first block that contains an "!". This and all the subsequent blocks of tests that contain an "!" symbol fail in the same way. None of the blocks before fails. Any hint? Thanks, Roberto -- Prof. Roberto Bagnara Applied Formal Methods Laboratory Department of Mathematical, Physical and Computer Sciences University of Parma, Italy http://www.cs.unipr.it/~bagnara/ mailto:bagnara@cs.unipr.it

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