- GiNaC-devel - ginac.de

After lifting the "no-bugs" ordinance...
by Richard B. Kreckel 19 Dec '01

19 Dec '01

...a couple of bugs were indeed discovered and fixed wich leeds us to the release of GiNaC-1.0.2, available at the usual places. It does not break compatibility with prior 1.0.n-versions. Enjoy -richy. -- Richard B. Kreckel <Richard.Kreckel(a)Uni-Mainz.DE> <http://wwwthep.physik.uni-mainz.de/~kreckel/>

1 0

Adding python support to GiNaC
by Pearu Peterson 19 Dec '01

19 Dec '01

Hi! I have been working on the python interface to GiNaC. It is quite usable already and I have tested it in many problems. However, it would be great if some python specific changes that I had to do in GiNaC, could be added to GiNaC. These changes include mostly printing expressions. Earlier I used hooks from GiNaC archive features to get desired output for python, but it was _very_ slow compared to the native GiNaC print hooks. So, please find a patch attached that adds two new print_context classes, print_python and print_python_repr, with the corresponding additions to print methods of the basic classes. The patch includes also the following change in the idx::print method for print_latex context: `a.b' becomes `a_{b}' if b is covariant, `a^{b}', otherwise (you can ignore it if you don't like it). This patch is against GiNaC-1.0.1. I can make it also against the latest GiNaC in CVS. Let me know if needed. Thanks, Pearu

2 2

Bug?: (a^b).unit(a) -> SIGSEGV
by Pearu Peterson 17 Dec '01

17 Dec '01

Hi, Notice that (a^b).unit(a) leads to Segmentation fault. I have failed to track down the source of this fault in GiNaC --- I would expect that this expression should throw an exception "invalid expression in unit()", but something gets wrong elsewhere. Any ideas? Pearu For your convinience, here is a sample program: #include <iostream> #include <ginac/ginac.h> using namespace std; using namespace GiNaC; int main() { symbol a("a"),b("b"); ex e = power(a,b); cout << "e="<<e<< endl; cout << "e.unit(a)="<<e.unit(a)<< endl; return 0; }

4 3

How to use sqrt for input expression?
by Hidehiro FUJIO 14 Dec '01

14 Dec '01

Dear GiNaC developers, I'm using GiNaC for making numerical simulation tools. My problem with GiNaC is how to handle 'sqrt' function in expression input. The simplest example is, ======================================= #include <ginac/ginac.h> using namespace GiNaC; #include <iostream.h> int main() { symbol x("x"); ex e("sqrt(x)",lst(x)); cout << e <<endl; } ======================================= When it runs, it makes core dump. When I use 'sin' instead of 'sqrt', the result is what I expected with GiNaC library. Is it a bug or normal? If normal, how to input expression that contains 'sqrt' function? Best regards, Hidehiro Fujio NEC Corporation, Internet System Laboratory Kawasaki, Japan 216-8555 E-mail: fujio(a)ccm.cl.nec.co.jp

2 1

invalid expression in content|unit|...()
by Pearu Peterson 08 Dec '01

08 Dec '01

Hi, While unit-testing pyginac, I found the following inconsistency: 1) define a = symbol("a") b = symbol("b") c = constant("c") 2) observe content(2,a) -> 0 (ok) content(2*a + 4*c,a) -> 2 (ok) content(a*c,a) -> exception 'invalid expression in unit()' ?! content(a*b,a) -> b (ok) 3) similar behaviour can be observed also for other functions like unit,.. The question is: Is it possible to unify the behaviour of the relevant functions? That is, to extend them to accept other objects in addition to symbol, numeric, add, etc. Or, to raise an exception whenever there are alien object in expressions. (Though, constants should not be alien when comparing them with symbols.) My argument to consider this inconsistency as a problem is that this behaviour is confusing and could lead to difficult-to-find bugs. Thanks, Pearu

3 6

Note on pseries::power_const() method.
by Pearu Peterson 28 Nov '01

28 Nov '01

Hi again, pseries::power_const() has second argument int deg that allows negative values of deg. If one calls this method with negative deg then the line co.reserve(deg); will cause MemoryError as (unsigned)deg gets really big. My questions are: 1) Is there any sense using negative deg? If yes, then the above indicates a bug. If no, then an exception should be thrown. 2) In case negative deg is valid, then is there a reason why power_const() method needs this argument (and methods mul_const(),etc don't)? In the interface to python, I have used the following rule to find the default value for deg: If p==pseries(...) and n is integer, then deg in p.power_const(n,deg) is found as follows ldeg = abs(n * p.ldegree(p.get_var())) deg = abs(n * p.degree(p.get_var())) deg = max(ldeg,deg) + 2 With this rule, I have found that equation (p^n)^m == p^(n*m) for all integers m,n (also negative). holds (and therefore seems sensible to me). Do you see any faults in this rule? Thanks, Pearu

2 2

Bug: ex(numeric(0)).series(x==0,2).is_zero() returns incorrectly 0
by Pearu Peterson 27 Nov '01

27 Nov '01

Hi! The explanation for this bug is that pseries defines its own is_zero() method that is not used within ex::is_zero() method. As a possible solution: define basic::is_zero() (with the contents of current ex::is_zero()) and redefine ex::is_zero() to call ex::bp->is_zero(). I guess that matrix class could also have its own is_zero() method. Pearu

1 0

Release 1.0.1 just hit the shelves
by Richard B. Kreckel 22 Nov '01

22 Nov '01

Okay, before heading off to Japan with Christian we spun version 1.0.1, which fixes a few things: * Function sqrfree() handles a few more cases now. * Class relational supports real canonical ordering now (thanks to Pearu). * Handle obscene libreadline version numbers when building ginsh. This release is compatible with version 1.0.0 where compatibility is defined as on the interface and binary levels. Some computational results might differ, though, as for instance sqrfree(-y*z*x+z*x^2+z^2*x-y*z^2) will now fully factorize to z*(z+x)*(-y+x) and not get stuck with (z^2+x*z)*(x-y). Remember that we are gone for the next twelve days, so don't bother reporting bugs. IOW: We officially declare this version bug-free till then. Happy hacking -richy. -- Richard B. Kreckel <Richard.Kreckel(a)Uni-Mainz.DE> <http://wwwthep.physik.uni-mainz.de/~kreckel/>

1 0

Is relational::is_equal patch needed?
by Pearu Peterson 22 Nov '01

22 Nov '01

Hi, I have noticed that relational(a,b,==).is_equal(relational(b,a,==)) returns 0 Is this expected behaviour for GiNaC internals? I just want to know whether it is worth to write a patch such that a==b .is_equal(b==a) -> 1 a<b .is_equal(b>a) -> 1 etc. that should be implemented in the method relational::is_equal_same_type right? Regards, Pearu Pearu Peterson <pearu(a)ioc.ee>, PhD, Researcher Department of Mechanics and Applied Mathematics http://cens.ioc.ee/~pearu/ Institute of Cybernetics at Tallinn Technical University Phone: (+372) 6204168 Akadeemia Rd. 21, 12618 Tallinn ESTONIA Fax: (+372) 6204161 *** the nonvalidity of rigorous causality is necessary and not just consistently possible (Heisenberg, 1925) ***

2 3

cln?
by keith.briggs＠bt.com 22 Nov '01

22 Nov '01

Dear GiNaC people, I wanted to install ginac1 so I had to upgrade my cln to the latest version (I used older version ok). But it would not compile on my redhat6 system. (see the attachment) Any ideas? I know you are not the cln authors, but maybe you have experience with this. Thank you, Keith <<cln-probs>> Dr. Keith M. Briggs Senior Mathematician, Complexity Research, BTexact Technologies email: Keith.Briggs(a)bt.com phone: +44(0)1473 work: 641 911 home (new!): 610 517 fax: 647 410 web: www.btexact.com/people/briggsk2/ mail: Keith Briggs, Antares 2pp5, Adastral Park, Martlesham, Suffolk IP5 3RE, UK BTexact Technologies is a trademark of British Telecommunications plc Registered office: 81 Newgate Street London EC1A 7AJ Registered in England no. 1800000 This electronic message contains information from British Telecommunications plc which may be privileged or confidential. The information is intended to be for the use of the individual(s) or entity named above. If you are not the intended recipient be aware that any disclosure, copying, distribution or use of the contents of this information is prohibited. If you have received this electronic message in error, please notify us by telephone or email (to the numbers or address above) immediately.

2 1