December 2002 - GiNaC-list

behaviour of find method.
by Chris Dams 06 Jan '03

06 Jan '03

Hello everybody, I found out that the behaviour of the find method is not quite as advertised in the tutorial. The tutorial says: @example bool ex::find(const ex & pattern, lst & found); @end example works a bit like @code{has()} but it doesn't stop upon finding the first match. Instead, it appends all found matches to the specified list. Appending means adding at the end. However, the code of the ex::find() method includes the lines if (match(pattern)) { found.append(*this); found.sort(); found.unique(); return true; } This sorts the found-list so that a match will most of the time not end up at the end, not to mention what happens to any ordering of elements the found list had before calling the find() method. I would guess that this is because this implementation comes with potentially huge memory savings at the cost of speed because of uniquing after every object found. If this is the case, I can understand the implementation, but still the tutorial should describe the true behaviour. Groetjes, Chris

2 1

Horrendous increase in compile times (gcc 2.95.2 vs gcc 3.2 -- MinGW versions)
by Richard Haney 15 Dec '02

15 Dec '02

I switched from gcc 2.95.2 to 3.2 -- Mingw versions -- and got a horrendous increase in compile times in subdirectory 'ginac'. Free space on my c: drive is 495 MB. (My RAM is limited to 32 MB because it seems that the circuitry for memory expansion has failed.) Is the gcc 3.2 compiler bumping hard against swapping size limits? A look at the 'system monitor' software during compilation seems to say that only 72 MB is used for swapping. Or is there something else that's causing this horrendous slowdown (like a bad compiler design in upgrading from 2.95.2 to 3.2 maybe?)? Here are a couple of tables with relevant info (listing object files with file sizes and creation times) for compiling in subdirectory ginac. Table 1 ***** * object modules created by gcc 3.2 in three continuous runs of make "--------" indicates interruption of make. (selected compile times in right hand column) (Making of power.o, operators.o, and the last ten minutes of numeric.o were done at a slower processor speed powered by an auxiliary battery. The rest of the makes were done at normal high speed using ac power; high speed is nominally 380 MHz, per user's manual; lower speed value unknown.) 1451471 Wed Dec 11 19:12:08 2002 power.o 914349 Wed Dec 11 18:17:08 2002 operators.o 1630236 Wed Dec 11 18:09:32 2002 numeric.o 1.3 hrs 1763843 Wed Dec 11 16:49:42 2002 normal.o 1.5 hrs 1351462 Wed Dec 11 15:18:02 2002 mul.o 1736244 Wed Dec 11 14:37:12 2002 matrix.o 1326684 Wed Dec 11 13:29:20 2002 inifcns_gamma.o 948098 Wed Dec 11 12:57:22 2002 inifcns_zeta.o 1675190 Wed Dec 11 12:53:10 2002 inifcns_trans.o 1415743 Wed Dec 11 11:47:16 2002 inifcns.o 1530210 Wed Dec 11 11:06:18 2002 function.o --------------------------------------------------------------------- 944331 Tue Dec 10 18:03:02 2002 fail.o 1359025 Tue Dec 10 17:58:14 2002 exprseq.o 1475200 Tue Dec 10 17:22:22 2002 expairseq.o --------------------------------------------------------------------- 885881 Tue Dec 10 14:56:32 2002 expair.o 3.2 min 967914 Tue Dec 10 14:53:18 2002 ex.o 8.5 1055734 Tue Dec 10 14:44:48 2002 constant.o 16.2 1124770 Tue Dec 10 14:28:34 2002 basic.o 20.3 1374322 Tue Dec 10 14:08:18 2002 archive.o 30.7 1203797 Tue Dec 10 13:37:38 2002 add.o Table 2 ***** * Object modules created by gcc 2.95.2 with continuous operation of make (selected compile times in right hand column) (normal high processor speed using ac power; high speed is nominally 380 MHz, per user's manual.) 274186 Tue Oct 08 17:25:36 2002 operators.o 1820796 Tue Oct 08 17:24:36 2002 numeric.o 7.1 min 1792847 Tue Oct 08 17:17:32 2002 normal.o 5.5 min 894707 Tue Oct 08 17:12:00 2002 mul.o 1581044 Tue Oct 08 17:10:10 2002 matrix.o 839184 Tue Oct 08 17:07:32 2002 inifcns_gamma.o 307886 Tue Oct 08 17:06:04 2002 inifcns_zeta.o 1572996 Tue Oct 08 17:05:06 2002 inifcns_trans.o 1034273 Tue Oct 08 17:01:40 2002 inifcns.o 1155709 Tue Oct 08 16:59:14 2002 function.o 188153 Tue Oct 08 16:57:44 2002 fail.o 744889 Tue Oct 08 16:57:02 2002 exprseq.o 1094132 Tue Oct 08 16:56:00 2002 expairseq.o 105948 Tue Oct 08 16:54:24 2002 expair.o 0.7 min 257110 Tue Oct 08 16:53:42 2002 ex.o 0.7 min 378665 Tue Oct 08 16:52:58 2002 constant.o 1.0 min 479942 Tue Oct 08 16:51:58 2002 basic.o 1.0 min 972535 Tue Oct 08 16:50:58 2002 archive.o 1.0 min 561407 Tue Oct 08 16:49:58 2002 add.o ================== Here is also a summary of similar results for compiling CLN modules: Statistics for gcc 3.2 v 2.95.2 for CLN object modules ********** *** *** ****** *** ****** ******* gcc 2.95.2 compilation of cln modules in subdir src: ****** Average compile time for the second through 27th module is 19 seconds. Average object module size for the first 27 modules is 18,896 bytes. Average object module size for all 855 modules is 67,125 bytes. -------------------------------- gcc 3.2 compilation of cln modules in subdir src: *** Average compile time for the second through 27th module is 2.3 minutes. Average object module size for the first 27 modules is 254,008 bytes. Average object module size for all 855 modules is 198,708 bytes. What can I do to get CLN & GiNaC built reasonably well? I again tried to make libreadline with gcc 2.95.2 (using new things I've learned) because 2.95.2 seems at present to be the best bet, but I still run into problems. It seems I need a new set of header files (and maybe gcc 2.95.2 libraries) or, preferably, a gcc 2.95.2 libreadline.a for win32 (i.e., MinGW). That would allow me to continue with using gcc 2.95.2. Richard Haney __________________________________________________ Do you Yahoo!? Yahoo! Mail Plus - Powerful. Affordable. Sign up now. http://mailplus.yahoo.com

2 1

why is GiNaC::symbol commutative??
by smilauer＠volny.cz 03 Dec '02

03 Dec '02

Hello, subject explains it all. I would like to use symbols to represent matrices. Obvious solution (replacing symbols via some_ex.sub(some_symbol==some_matrix) does not work for multiplication of matrices. Other ways to do it? Thanks. Vaclav. (If I understand it right, upon replacement of one matrix, one has matrix*symbol; symbol is supposed to be a scalar, so we have commutative multiplication; then the other symbol is also substituted for a matrix, so one gets exception "non-commutative scalar".)

2 1