June 2002 - GiNaC-list

More Spam...
by Richard B. Kreckel 28 Oct '02

28 Oct '02

Dear folks, We apologize for the #@&*%! Spam you received through this list. Please bear with us while a solution (likely SpamAssassin) will be deployed. Meanwhile, since it hasn't been on our lists yet, I am pleased to spam you with some shameless ad about the Workshop on Open Source Computer Algebra Tuesday 21st - Thursday 23rd of May 2002 Lyon, France <http://www.lapcs.univ-lyon1.fr/~nthiery/CalculFormelLibre/workshop.html> Hurry up, in case you are interested. ¡Hasta la vista! -richy. -- Richard B. Kreckel <Richard.Kreckel(a)Uni-Mainz.DE> <http://wwwthep.physik.uni-mainz.de/~kreckel/>

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segmentation fault in simplify_indexed --> solved?
by Chris Dams 25 Jun '02

25 Jun '02

Hello everybody, I think I have solved an error in GiNaC that sometimes (only in special circumstances) causes a segmentation fault when *simplify_indexed* is called. The problem occurs when the function *diracgamma::contract_with* is sometimes called with the arguments *self* and *other* pointing to two gamma matrices of different representation label. In that case it can happen that there is a gamma5 in between and that the function *base_and_index* is called with the gamma5 in its first argument. This is wrong because base_and_index tries to look at operand number 1, which does not exist for a gamma5. This then may cause a segmentation fault. It never happens for gamma matrices of the same rep. label because the gamma5 has been permuted out of the way then. I found that the segmentation fault dissapears when inside the first *if* in *diracgamma::contract_with* I add a test that checks if rep. labels are equal (the contract-gamma-matrices algorithms there, do not seem to make much sense if rep. lables are different anyway). After my addition the code looks like if (is_a<clifford>(*other)) { unsigned char rl2 =ex_to<clifford>(*other).get_representation_label(); if(rl!=rl2) return false; ex dim = ex_to<idx>(self->op(1)).get_dim(); where the first and last line are yours and the three in the middle are mine. (BTW this is GiNaC-1.0.8). Greetings, Chris

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GiNaC 1.0.9 now available (AKA Episode I - The Indexed Menace)
by Christian Bauer 11 Jun '02

11 Jun '02

FADE IN EXT. UNIVERSITY BUILDING - EVENING It is a quiet, hot summer evening. The setting sun casts its last rays on the Physics Department building, giving the stone walls a wonderful warm golden glow. The only sounds that are heard are the raspy cries of a black swarm of ravens that circles in the sky. Two cyclists ride down the street in front of the building. CUT TO INT. UNIVERSITY BUILDING, OFFICE - CONTINUOUS There are numerous desks and computers in this small, dimly lit room in the fifth floor of the Physics Department building. The walls are lined with large cupboards, science fiction posters, GiNaC logo designs and hardcopies of 'Dilbert' cartoons. Quiet piano music fills the air. Only two people are still working at this time of day. One, RICHY K. is sitting in a corner of the room, close to the window, with his bare feet laid on top of the desk and a notebook computer in his lap. The other, CHRISTIAN B., is busy studying eBay article listings on one of two monitors on his desk in the middle of the room. RICHY K. presses a few keys on his notebook and takes a sip from a cocktail glass. Then he speaks without turning his eyes away from the screen. RICHY K. There's a tarball at the usual place now. CHRISTIAN B. Cool... CHRISTIAN B. clicks on the 'shell' icon on his computer's desktop and starts typing commands. CHRISTIAN B. So we're going to release today? RICHY K. Yup. He brings up a Mozilla window displaying the Slashdot front page on his notebook. CHRISTIAN B. Did you put the champagne in the fridge? RICHY K. Pardon? CHRISTIAN B. (louder) Did you put the champagne in the fridge? RICHY K. We don't have any champagne. CHRISTIAN B. How can we release without champagne? RICHY K. Only drinking all the time... CHRISTIAN B. types some more commands. CHRISTIAN B. Is this 1.1.0? RICHY K. Nope, 1.0.9. CHRISTIAN B. Will we have champagne when we get to 1.1.0? RICHY K. Maybe... CHRISTIAN B. slams down the 'Return' key on his keyboard and leans back. Progress messages of a compiler run start scrolling down the screen. He returns his attention to the eBay listings on the second monitor. CHRISTIAN B. They're selling an eight-CPU Origin for 180,000 here... RICHY K. Cool. Tell Hubert to buy it. CHRISTIAN B. Where is Hubert, anyway? RICHY K. I don't know... RICHY K. takes another sip from his orange-red cocktail. CHRISTIAN B. glances over the compiler output but then looks back at his browser window and types in a URL. CHRISTIAN B. Did you get yesterday's User Friendly? RICHY K. What? CHRISTIAN B. (louder) Yesterday's User Friendly. Did you understand the punch line? RICHY K. Nope. CHRISTIAN B. What does that Russian sentence mean? RICHY K. Don't know. CHRISTIAN B. You ought to know. You've been in Russia. RICHY K. They all spoke English there. CHRISTIAN B. Oh. The compiler run is still in progress. CHRISTIAN B. grabs his coffee mug, slowly stands up, and walks over to the coffee machine. After filling the mug he returns to his place. CHRISTIAN B. You're already writing the announcement? RICHY K. It's your turn this time. CHRISTIAN B. No, it's not. I wrote the announcement for 1.0.8. RICHY K. No, you didn't. I did. It's your turn now. CHRISTIAN B. It's always 'my turn'. Why is it always my turn? RICHY K. It isn't. You're only trying to sneak out of having to write it. CHRISTIAN B. I'm not. He turns back to the monitors. Seeing that the compiler run has finished successfully, he continues to enter commands. CHRISTIAN B. RPM builds fine. I'll move it to the FTP server. RICHY K. Pardon? CHRISTIAN B. (louder) I will upload the RPM to the FTP server. RICHY K. Suit yourself... CHRISTIAN B. Did you tag the CVS? RICHY K. gasps with ostentation and starts pressing keys. RICHY K. Tagged. CHRISTIAN B. Nearly... CHRISTIAN B. still hacks away at his keyboard. RICHY K. Are you writing the announcement now? CHRISTIAN B. It's your turn. Besides, I can't write announcements without champagne. RICHY K. There should still be some wine in the cupboard. CHRISTIAN B. turns around to the cupboard behind him and opens the lower door. His face brightens up when he sees several bottles of red and white wine. CHRISTIAN B. (smiling) I'll write the announcement... FADE OUT

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