- GiNaC-list - ginac.de

Converting an expression to std::string and back again
by Robert Hai 29 Mar '17

29 Mar '17

Dear Mailing List, for a project I need to convert a std::string to an ex, diff it and then convert it back to a std::string. For the conversion from std::string to ex I found this constructor : /** Construct example from string and a list of symbols. The input grammar is * similar to the GiNaC output format. All symbols and indices to be used * in the expression must be specified in a lst in the second argument. * Undefined symbols and other parser errors will throw an exception. */ ex(const std::string &s, const ex &l); at http://www.ginac.de/reference/classGiNaC_1_1ex.html#ace68037326c1a2b8c93a56… So I tried doing the following : symbol x("x"); ex expression; ex e("x^2",expression); std::cout << diff(e,x) << std::endl; But this leads me to this exception : std::invalid_argument: find_or_insert_symbol: symbol "x" not found Note that I tried using expression and e in diff(e,x). Unfortunately I could not find any documentation on how to convert the expression diff returns to a std::string. Thanks a lot for your help in advance ! Robert Hey

2 4

Error on expression
by Jean-Michaël Celerier 14 Mar '17

14 Mar '17

The following code produces an error that says that it should be reported : #include<ginac/ginac.h> #include<iostream> int main(int argc, char* argv[]) { GiNaC::symtab table; table["x"] = 2.34; GiNaC::parser p(table); GiNaC::ex e = p("2*cos(x)+e^x"); GiNaC::numeric n = GiNaC::ex_to<GiNaC::numeric>(e); double x = GiNaC::ex_to<GiNaC::numeric>(n.evalf()).to_double(); std::cout << x << std::endl; return 0; } The error : terminate called after throwing an instance of 'cln::notreached_exception' what(): Internal error: statement in file real/elem/cl_R_mul.cc, line 93 has been reached!! Please send the authors of the program a description how you produced this error! Best Jean-Michaël

2 1

compile-time calculations
by Matteo 28 Feb '17

28 Feb '17

Hello, I am currently evaluating GiNaC for use in an engineering software that we use internally. Therefore, I am still inexperienced with it and only ask for some pointers. I have read in the news feed http://www.ginac.de/News.html that new C++11 features like "constexpr" are being implemented into GiNaC. My question is: how much can be done at compile time? Background: The basic workflow that we would like to optimize is the following: 1) Design an algorithm in C++, which involves manipulation of scientific formulae 2) Elaborate the "manipulation" part in a separate environment (mostly SageMath) 3) Translate the result of the separate CAS as C++ 4) Integrate the result into the original C++ algorithm This works, but has the following disadvantages: - it requires to leave one environment (C++ IDE) to the other (CAS environment) - translating the mathematical results to C++ is tedious and error prone (although it can be automated for simple cases) - it separates the various parts of the algorithm into different documents, which makes it hard to mantain Ideally then, we would use GiNaC instead of SageMath (or other CAS) to unify the code. However, we would like to remove the runtime overhead of expression manipulation and interpretation. I am looking for something like the "compilation of expressions to function pointers", but with the addition of compile-time expression manipulation. http://www.ginac.de/tutorial/#Compiling-expressions-to-C-function-pointers The closest I have found so far is ViennaMath, but it seems still very limited in features. http://viennamath.sourceforge.net/viennamath-example-integration.html Thank you for any help!

1 0

Re: [GiNaC-list] problems with cstring and string
by Tania Robens 09 Feb '17

09 Feb '17

ok i will try this i did install cln locally and configured with something like export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$CLN/lib ./configure --prefix=/home/trobens/programs/ginac/install CLN_CFLAGS=-I$CLN/include/cln/ CLN_LIBS=-L$CLN/lib/ CPPFLAGS=-I$CLN/include/ LDFLAGS=-L$CLN/lib/ LIBS=-lcln mb this causes the problem ?? On Thu, 9 Feb 2017, Mario Prausa wrote: > > > On 09.02.2017 03:51, Tania Robens wrote: >> >> In file included from >> /home/trobens/programs/cln/install/include/cln/string.h:9:0, >> from >> /opt/rh/devtoolset-3/root/usr/include/c++/4.9.2/cstring:42, >> from class_info.h:27, >> from registrar.h:26, >> from basic.h:29, >> from ex.h:26, >> from expair.h:26, >> from expairseq.h:26, >> from add.h:26, >> from add.cpp:23: >> > > This looks suspicious. The ginac file "class_info.h" includes the > standard C++ library file "cstring" which includes the CLN file > "string.h". In the standard C libray there is also a file by the name > "string.h" which is what "cstring" wants to include. > > I think the problem is the order of your include pathes. The pathes to > the standard libraries should go before any other libraries (in that > case CLN). > > Mario > ------------------------------------------------------------------------- Dr. habil. Tania Robens Michigan State University Department of Physics and Astronomy 567 Wilson Road East Lansing, MI 48824 USA

3 3

problems with cstring and string
by Tania Robens 09 Feb '17

09 Feb '17

Hi I have tried to implement the newest CLN version (cln-1.3.4) and ginac version (ginac-1.7.2). i am using gcc (GCC) 4.9.2 20150212 (Red Hat 4.9.2-6) (but also had the same problem with newer compilers) uname -a renders Linux 2.6.32-642.11.1.el6.x86_64 #1 SMP Tue Nov 15 14:13:21 CST 2016 x86_64 x86_64 x86_64 GNU/Linux CLN works, but for ginac i get checking readline/readline.h usability... no checking readline/readline.h presence... yes configure: WARNING: readline/readline.h: present but cannot be compiled configure: WARNING: readline/readline.h: check for missing prerequisite headers? configure: WARNING: readline/readline.h: see the Autoconf documentation configure: WARNING: readline/readline.h: section "Present But Cannot Be Compiled" configure: WARNING: readline/readline.h: proceeding with the compiler's result configure: WARNING: ## ---------------------------------- ## configure: WARNING: ## Report this to ginac-list(a)ginac.de ## configure: WARNING: ## ---------------------------------- ## checking for readline/readline.h... no checking readline/history.h usability... no checking readline/history.h presence... yes configure: WARNING: readline/history.h: present but cannot be compiled configure: WARNING: readline/history.h: check for missing prerequisite headers? configure: WARNING: readline/history.h: see the Autoconf documentation configure: WARNING: readline/history.h: section "Present But Cannot Be Compiled" configure: WARNING: readline/history.h: proceeding with the compiler's result configure: WARNING: ## ---------------------------------- ## configure: WARNING: ## Report this to ginac-list(a)ginac.de ## configure: WARNING: ## ---------------------------------- ## checking for readline/history.h... no and, when i ignore this and do make anyways, i have In file included from /home/trobens/programs/cln/install/include/cln/string.h:9:0, from /opt/rh/devtoolset-3/root/usr/include/c++/4.9.2/cstring:42, from class_info.h:27, from registrar.h:26, from basic.h:29, from ex.h:26, from expair.h:26, from expairseq.h:26, from add.h:26, from add.cpp:23: /opt/rh/devtoolset-3/root/usr/include/c++/4.9.2/cstring:75:11: error: ‘::memchr’ has not been declared using ::memchr; ^ /opt/rh/devtoolset-3/root/usr/include/c++/4.9.2/cstring:76:11: error: ‘::memcmp’ has not been declared using ::memcmp; ...etc ... which then leads to a stop in the compilation. i have tried various ways around this, if someone has a quick solution please let me know the same mistake occurs with earlier ginac versions and, as stated, with newer gccs (up to 6.1) ?? Thanks Best Tania Robens ------------------------------------------------------------------------- Dr. habil. Tania Robens Michigan State University Department of Physics and Astronomy 567 Wilson Road East Lansing, MI 48824 USA

3 3

About non commutative transformations in GiNaC
by abpetrov 26 Jan '17

26 Jan '17

Hello, I wrote a program to do calculations with non commutative variables in GiNaC. But when I made attempt to apply noncommutative rule I got error: terminate called after throwing an instance of 'std::logic_error' what(): add::eval(): sum of non-commutative objects has non-zero numeric term Below is simple example of program with program output. How to change the class ncsymbol so that it was possible to apply rules like a*ap==ap*a+1? Best regards Petrov A.B. -------------------------------------------------------------------- Output for program: Starting: ./test2 e1: a*ap*a terminate called after throwing an instance of 'std::logic_error' what(): add::eval(): sum of non-commutative objects has non-zero numeric term *** Crashed with return code: 0 *** ------------------------------------------------------------------ Program: #include <iostream> using namespace std; #include<ginac/ginac.h> using namespace GiNaC; class ncsymbol : public symbol { GINAC_DECLARE_REGISTERED_CLASS(ncsymbol, symbol) public: ncsymbol(const string &s); protected: unsigned return_type() const { return return_types::noncommutative_composite; } }; GINAC_IMPLEMENT_REGISTERED_CLASS(ncsymbol, symbol) ncsymbol::ncsymbol() { } ncsymbol::ncsymbol(const string &s) : inherited(s) { } int ncsymbol::compare_same_type(const basic &other) const { GINAC_ASSERT(is_a<ncsymbol>(other)); const ncsymbol *o = static_cast<const ncsymbol *>(&other); if (serial==o->serial) return 0; return serial < o->serial ? -1 : 1; } void calc_example(){ ncsymbol a("a"),ap("ap"); ex e1 = a*ap*a; cout << "e1: " << e1 << endl; e1 = e1.subs(a*ap==ap*a+1); cout << "e1 subs: " << e1 << endl; } int main(int argc, char** argv) { calc_example(); return 0; }

2 4

Automatic transformation of expressions in GiNaC
by abpetrov 12 Jan '17

12 Jan '17

Hello, I wrote some program to do some calculations with GiNaC. But I can see program makes some unwanted transformations of expressions automatically. Below is simple example. Can I avoid that transformations? Wanted output is sqrt(m/2). Best regards Petrov A.B. -------------------------------------------------------------------- Output for program: Starting: ./test2 1/2*sqrt(2)*sqrt(m) *** Exited normally *** ------------------------------------------------------------------ Program: #include <iostream> using namespace std; #include<ginac/ginac.h> using namespace GiNaC; void calc_example(){ possymbol m("m"); ex e = sqrt(m/2); cout << e << endl; } int main(int argc, char** argv) { calc_example(); return 0; }

2 2

Release 1.7.2
by Richard B. Kreckel 10 Jan '17

10 Jan '17

Hi, A new GiNaC release is out and available. These are the changes: * Fix memory leak in operators returning relationals, introduced in 1.7.0. * Make macro GINAC_DECLARE_REGISTERED_CLASS() work outside namespace GiNaC. * Fix some build issues. Happy hacking -richy. -- Richard B. Kreckel <http://in.terlu.de/~kreckel/>

1 0

Memory leak in dynallocate for relational
by Thomas Luthe 09 Jan '17

09 Jan '17

Hi, valgrind reports a memory leak caused by dynallocate<GiNaC::relational, const GiNaC::ex&, const GiNaC::ex&, GiNaC::relational::operators> (basic.h:336). I have attached a minimal example as well as the corresponding valgrind output I get. The executable was produced with g++ 5.4 -O0 and GiNaC 1.7.1. Repeated use of operators == or != for GiNaC::ex does indeed lead to a noticeable increase of memory usage in applications, whereas ex::is_equal does not have the same effect. Cheers, Thomas

2 1

Simplification in GiNaC
by abpetrov 07 Jan '17

07 Jan '17

Hello, I recently wrote a simple program to learn some calculations with GiNaC. This works, But I got some expression which automatically don't become simple. The question is: What is the simplest way to get the expected answer - Ax here? Best regards Petrov A.B. -------------------------------------------------------------------- Output for program: Starting: ./test2 sqrt(m*x^2*A)*sqrt(m^(-1)*A) *** Exited normally *** ------------------------------------------------------------------ Program: #include <iostream> using namespace std; #include<ginac/ginac.h> using namespace GiNaC; void calc_example(){ realsymbol A("A"),m("m"),x("x"); ex e = sqrt(A*m*pow(x,2))*sqrt(A/m); cout << e << endl; } int main(int argc, char** argv) { calc_example(); return 0; }

2 2