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Is GiNaC really that dirty?
by Chris Dams 17 Jul '01

17 Jul '01

Hello everybody, I have been playing around with ginac a bit, but the impression that I get from the tutorial is that one has to write really dirty code to get something done. Since it is not my intention to start a flame war based on vague sentences like the previous one, I will give an example of a function I want to write. The answer I am hoping for is something like: ``No, you stupid, you don't need to write things like that. It can be done much more beautifull, namely like this: ......'' To be more concrete, I want to write the function ex checkdeg(ex f,ex var,int n) which expects that *f* is a polynomial in expanded form in a variable in *var* and perhaps other variables. The return value is the same polynomial except that all terms in which *var* occurs in a power higher than *n* are discarded. Maybe you want to compare the function I have written to accomplish this with the FORM statement id var^m?{>n}=0; which does the same thing. ``Comparing'' especially with respect to its length and elegance. I want to make it a *map_function*. Now I have a problem since *map_function*s only have one argument. The solution I came up with looks like struct Checkdeg:public map_function { ex var; int n; ex operator()(const ex&f,ex v,int nint) { var=v; n=nint; return (*this)(f); } ex operator()(const ex&f) { ... Here comes the code that actually does something ... } } checkdeg; which looks somewhat queer. I really would like to be able to say something like return f.map(*this)(var,n) or maybe like this return f.map((*this)(var,n)) Well, you get the idea. I want to map a function with more than just one argument. Now after having ``solved'' the problem of writing the *map_function*, now let us consider the the function ex operator()(const ex&f) This function first checks whether *f* is an addition and then uses the *map* function to tell ginac that it should treat each term seperately. No problem here anymore. Then we have the case were *f* is not an addition. I really would want to write someting like lst repls; return f.match(wild(0)*pow(var,wild(1)),repls) if(repls.op(1)>n) f.subs(var==0); but then I discover that *pow(var,m)* is not mathched since it is not a product. I really cannot imagine any reason whatsoever why not to automatically consider something that is not a product as a product with a single factor in patern matching against a product. It would make code so much more elegant, and cannot be really difficult or inefficient. The same thing with the power. The manual mentions something like ten times that one may not use the pattern *pow(var,wild(1))* to match the expression *var*. Why on earth not? The cynical remark would be that if something needs to be said ten times, it can hardly be something you want to hear. A solution to this problem would seem to be using the *.has* method, but then again, this one does not return the thing that matches the wildcard. So I have to use the *.find* method. Then I have to interpret the list it returns. This I have to do by writing an *if* like if(repls.op(0).op(1)>n) to check the first element in the list, which contains an expression like *var^m* and get the *m* out of this. This is may be only slightly inelegant, but I think it is inelegant. Why does the *.find* method return the entire match expression, why not simply the thing that is equal to the wildcard. It would change my *if* into if(repls.op(0)>n) which is somewhat shorter (but in complicated expressions could be very much sorter). In my opinion the user can generally be expected to know the expression againts which he matches, so why does he have to dissemine that one again when he reads the result from the match? It simply does not give any new information. Furthermore it is inconsistent since the match method indeed only returns the values of the wildcards. The only objection I could imagine is that the *find* function could return more than one match. This is true, but in this case one could return {{value of $0,value of $1},{value of $0,value of $1}} Indeed, now I would have to write down exactly the same test, but the advantage is that I don't need to know that the exponent of a power is stored in *.op(1)*, which I really don't want to and shouldn't need to know as an ordinary user. After these considerations I felt I had to write something like ex operator()(const ex&f) { if(is_a<add>(f)) return f.map((*this)(var,n)); switch(n) { case 0: return f.subs(var==0); case 1: return f.subs(pow(var,wild())==0); default: lst repls; if(f.find(pow(var,wild()),repls)) { if(repls.op(0).op(1)>n) return f.subs(var==0); else return f; } else return f; } } for my function. Now I guess the whole *struct Checkdeg* is at least thrice as long as the thing I saw before me in my dreams. Does it really have to be that dirty? Greetings, Chris Dams

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configure cannot find headers for libreadline
by Chris Dams 12 Jul '01

12 Jul '01

Hello everybody, Configure cannot find the headers for libreadline, although they are definately present. I tried setting the CPPFLAGS as in setenv CPPFLAGS -I/usr/locacal/gnu/include ./configure --prefix=/home/thef/chrisd/c++ but still configure does not find them. Does somebody know how to solve this problem? Note: I am on a unix where I am not allowd to set symlinks in system include dirs. (If this were allowed, I would probably not be posting anything here). Greetings, Chris Dams

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error while loading shared libraries: libcln.so.2
by Wolfgang 06 Jul '01

06 Jul '01

I've done a standard installation (no flags, no special directories) of cln 1.1.1 with gcc 2.96. After 'make check' it said 'All tests passed'. Now I can compile a cln example file, but when I want to run the binary I get the above error message. Do I have to set certain gcc flags when compiling the example file, or how can solve that problem? Thank you for your help! Wolfgang - To UNSUBSCRIBE, email to ginac-list(a)ginac.de with a subject of "unsubscribe".

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Polynomials
by Wolfgang Abele 04 Jul '01

04 Jul '01

How can I set the coefficient domain of polynomials? Say, I want my coefficients to be in Z mod 17, i.e. Galois Field 17, what do I do? Also, as a more general question, I'd like to know if GiNac poses any overhead on the polynomial classes provided by CLN. In other words, it is less efficient to write polynomials routines in Normal.cpp (the polynomial module in GiNac) than directly work with the CLN classes? Thanks in advance for your answers! Wolfgang - To UNSUBSCRIBE, email to ginac-list(a)ginac.de with a subject of "unsubscribe".

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Ginsh installation problem
by Wolfgang Abele 03 Jul '01

03 Jul '01

> Another solution would be to set the LD_LIBRARY_PATH environment > variable to include the directory where CLN library is located. This > would allow you to move CLN easier. Thank you, Ben, for your quick answer! I set that variable, and my cln program runs fine now Here's my next problem: I cannot install Ginac: After I enter 'make', gcc 2.96 outputs numerous warnings such as /usr/local/include/readline/rltypedefs.h:73: `rl_intfunc_t` declared with an exception specification and eventually stops with error messages; ginsh_parser.yy:769: 'filename_completion_function' undeclared ginsh_parser.yy:769: 'completion_matches' undeclared ginsh_parser.yy:824: 'cannot convert char **(+) () 'to char **(*) in (const char *, int, int) assignment I have readline 4.2. Wolfgang - To UNSUBSCRIBE, email to ginac-list(a)ginac.de with a subject of "unsubscribe".

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empty list
by tilman 29 Jun '01

29 Jun '01

Hello, Just one short question: is it possible to create an empty GiNaC list? Everything I tried so far failed.. Thanks Tilman - To UNSUBSCRIBE, email to ginac-list(a)ginac.de with a subject of "unsubscribe".

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GiNaC 0.9.1 released
by Christian Bauer 28 Jun '01

28 Jun '01

MAIN SCREEN TURN ON. HOW ARE YOU GENTLEMEN!! WHAT HAPPEN? YOU ARE ON THE WAY TO NEW FEATURES: * Ctors of class numeric are not explicit any more. All built-in callers for pseudofunctions are now templated and default to ex arguments which relaxes the need for explicit ctors. * New functions/methods: - find() - remove_first(), remove_last(), sort() and unique() for lists - symmetrize_cyclic() - decomp_rational() * Instead of just totally symmetric or antisymmetric, complex symmetries can now be defined for indexed objects. Symmetries are described by a tree of "symmetry" objects that is constructed with the sy_none(), sy_symm(), sy_anti() and sy_cycl() functions. The symmetry of a function with respect to its arguments can also be defined (this is currently only used for the Beta function). * Generalized map() to take a function object instead of a function pointer. This allows passing an arbitrary number of additional state to the function being called. * color_trace(), dirac_trace(), diff(), expand(), evalf() and normal() work better with container classes, e.g. using color_trace() on a relation will take the trace on both sides, using diff() on a matrix differentiates every element etc. * diff() works properly with non-commutative products and indexed objects. * New option flag "expand_function_args" for expand(). * Supplement some (now deprecated) macros by inlined template functions: - is_of_type(foo, type) -> is_a<type>(foo) - is_ex_of_type(foo, type) -> is_a<type>(foo) - is_exaclty_of_type(foo, type) -> is_exaclty_a<type>(foo) - is_ex_exaclty_of_type(foo, type) -> is_exaclty_a<type>(foo) - ex_to_foobar(baz) -> ex_to<foobar>(baz) * rem(c, p[x], x) (c: numeric, p[x]: polynomial) erroneously returned p[x] instead of c. * Small bugfixes in pattern matching. * Updated libtool to version 1.4. WHAT YOU SAY? DOWNLOAD EVERY 'GINAC': ftp://ftpthep.physik.uni-mainz.de/pub/GiNaC FOR GREAT JUSTICE, Christian -- / Coding on PowerPC and proud of it \/ http://www.uni-mainz.de/~bauec002/ - To UNSUBSCRIBE, email to ginac-list(a)ginac.de with a subject of "unsubscribe".

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Release 0.9.0 just hit the web
by Richard B. Kreckel 07 Jun '01

07 Jun '01

Go, grab your copy now, as long as supply lasts! Don't let others snatch away the few copies left at <ftp://ftpthep.physik.uni-mainz.de/pub/GiNaC/>! Hurry!!! Pronto!! ¡Rapido! Los! The NEWS file says: * In the output and in ginsh, lists are now delimited by { } braces, and matrices are delimited by single [ ] brackets. * simplify_indexed() renames dummy indices so, e.g., "a.i*a.i+a.j*a.j" gets simplified to "2*a.i*a.i" (or "2*a.j*a.j"). * New functions/methods: - canonicalize_clifford() (helpful when comparing expressions containing Dirac matrices) - symmetrize() and antisymmetrize() - numer_denom() (return numerator and denominator in one call) - map() (apply function to subexpressions) - evalm() (evaluate sums, products and integer powers of matrices) * Added a new function match() for performing pattern matching. subs() and has() also accept patterns as arguments. A pattern can be any expression, optionally containing wildcard objects. These are constructed with the call "wild(<unsigned>)" and are denoted as "$0", "$1" etc. in the output and in ginsh. * Positive integer powers of non-commutative expressions (except matrices) are automatically expanded. * Removed cint subdirectory, ginaccint is a separate package now due to packaging considerations. * Several little bugfixes. * More exclamation marks than ever in the announcement. - To UNSUBSCRIBE, email to ginac-list(a)ginac.de with a subject of "unsubscribe".

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Expand does not expands?
by zellerin＠winbase.software602.cz 28 May '01

28 May '01

Hello, I got to GiNaC only recently, and I have some troubles with the expand() function. I would expect following code -------- #include <ginac/ginac.h> using namespace GiNaC; symbol x("x"), y("y"); ex laplace_in_oblates(const ex& potential) { ex x_part=diff((x*x-1)*diff(potential,x), x); ex y_part=diff((1-y*y)*diff(potential,y), y); return normal(x_part+y_part); } int main() { ex R=sqrt(x*x+y*y-1); ex tmp=expand(pow(R, 5)*laplace_in_oblates(1/R)); cout << tmp<<" = "<<tmp.normal() << endl; return 0; } --------- to yield 0 = 0, but it gives 3*(-1+x^2+y^2)*y^2-3*x^2+3*x^4-3*(-1+x^2+y^2)*x^2-3*y^4+3*y^2 = 0 I would say that the polynomial on the left side is not expanded, in spite of the fact that it should be result of an expand. Anyone give me a hint what I am doing/expecting wrong? (tried on GiNaC version 0.6.4 on RedHat Linux 6.1 and GiNaC 0.8.3 on RH 7.1) Thanks Tomas Zellerin - To UNSUBSCRIBE, email to ginac-list(a)ginac.de with a subject of "unsubscribe".

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GiNaC build error (non-local fct uses anonymous type)
by george moudry 15 May '01

15 May '01

Hello GiNaC! I downloaded GiNaC-0.8.3.tar.bz2, but I'm having trouble building it on my system. My computer has SuSE 7.1 with gcc version 2.96 20000731. Here's the build error: make[2]: Entering directory `/home/gg/down2/math/GiNaC-0.8.3/ginac' /bin/sh ../libtool --mode=compile c++ -DHAVE_CONFIG_H -I. -I. -I.. -I/usr/local/include -g -O2 -c inifcns.cpp rm -f .libs/inifcns.lo c++ -DHAVE_CONFIG_H -I. -I. -I.. -I/usr/local/include -g -O2 -c inifcns.cpp -fPIC -DPIC -o .libs/inifcns.lo In file included from inifcns.cpp:31: matrix.h:125: non-local function `GiNaC::ex GiNaC::determinant (const GiNaC::matrix &, unsigned int = GiNaC::determinant_algo::automatic)' uses anonymous type make[2]: *** [inifcns.lo] Error 1 make[2]: Leaving directory `/home/gg/down2/math/GiNaC-0.8.3/ginac' make[1]: *** [all-recursive] Error 1 make[1]: Leaving directory `/home/gg/down2/math/GiNaC-0.8.3' make: *** [all-recursive-am] Error 2 Thanks for any help, /george moudry los angeles PS. I saw on the ginac.de website that some people were installing an RPM. Would you know where to download it from? PPS. The GiNaC screenshot is incredible! I really did think it crashed my browser. - To UNSUBSCRIBE, email to ginac-list(a)ginac.de with a subject of "unsubscribe".

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