## reduce-algebra-developers — Discussion of development, administration and support for Reduce

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Showing 3 results of 3

 Re: [Reduce-algebra-developers] Merely loading avector hurts other code From: René Grognard - 2012-02-17 04:14:15 ```Two comments: [1] orthovec uses >< for the cross product; [2] However excalc uses ^ for the "wedge" (exterior) product which is essential to modern differential geometry and excal is perhaps one of the very few symbolic packages freely available and advanced enough to be of real use by people doing research in that subject. Regards, René Grognard. On 2/16/12, Arthur Norman wrote: > 1: load_package avector; > > *** ^ redefined > > 2: on backtrace; > > 3: int(1/(x^6-1), x); > +++ Error: getv nil > Inside: vectorcrossprod > Arg1: (x 6) > apply: vectorcrossprod > Inside: vecsm!* > Arg1: (cross x 6) > Inside: vecsm!* > Arg1: (difference (cross x 6) 1) > Inside: vecsm!* > Arg1: (quotient 1 (difference (cross x 6) 1)) > Inside: vecsm!* > Arg1: (int (quotient 1 (difference (cross x 6) 1)) x) > > 4: > > I am posting this so it is in the list of things to deal with sometime - > is there an "avector" expert in the house? Well actually I guess this is > just that avector changes the syntax so that "x^6" is a cross product not > a power of x, but this really seems to me to be a horrid trap and a > substantial number of the test scripts use "^" rather than "**". > > The simplest patch I can think of at present is to make the syntax in > avector use say ^^ for a cross product rather than merely ^. That would be > an incompatible change that would hurt avector users but would make it > easier for people who do not use avector at present to load the package > and maybe sometimes benefit from it. > > Thoughts about that - or other solutions? And suggestions for a procedure > for deciding that changes that break things for some people can be > accepted - it feels dangerous to take unilateral action. > ```
 [Reduce-algebra-developers] Merely loading avector hurts other code From: Arthur Norman - 2012-02-16 07:59:38 ```1: load_package avector; *** ^ redefined 2: on backtrace; 3: int(1/(x^6-1), x); +++ Error: getv nil Inside: vectorcrossprod Arg1: (x 6) apply: vectorcrossprod Inside: vecsm!* Arg1: (cross x 6) Inside: vecsm!* Arg1: (difference (cross x 6) 1) Inside: vecsm!* Arg1: (quotient 1 (difference (cross x 6) 1)) Inside: vecsm!* Arg1: (int (quotient 1 (difference (cross x 6) 1)) x) 4: I am posting this so it is in the list of things to deal with sometime - is there an "avector" expert in the house? Well actually I guess this is just that avector changes the syntax so that "x^6" is a cross product not a power of x, but this really seems to me to be a horrid trap and a substantial number of the test scripts use "^" rather than "**". The simplest patch I can think of at present is to make the syntax in avector use say ^^ for a cross product rather than merely ^. That would be an incompatible change that would hurt avector users but would make it easier for people who do not use avector at present to load the package and maybe sometimes benefit from it. Thoughts about that - or other solutions? And suggestions for a procedure for deciding that changes that break things for some people can be accepted - it feels dangerous to take unilateral action. ============== load_package invbase; in "packages/alg/alg.tst"; fails with "fluid gg invalid as array" because invbase make gg fluid. I bet other packages make things fluid in ways that gratuitously pollute the name-space for users. Again does anybody have a neat suggestion for a way to improve matters? In this case I can just rename the variable in invbase to be "more obscure" (eg say invbase_gg) and not feel too nervous, but it would be good to detect and mend ALL such cases! Arthur ```
 [Reduce-algebra-developers] Quote from the REDUCE Newsletter number 10, September 1985 From: Arthur Norman - 2012-02-02 14:52:25 ```Back then Tony Hearn wrote "In a paper I gave at the 1980 IFIP Congree. I prediccted that by the mid 1980' it would be possible to obtain a complete compting system (both hardware and software) that could run programss like REDUCE for prices in the \$10,000-\$20,000 range. ..." He goes on to look at the encouraging prospect of offerings below even \$5000, and goes on to provide timings for running the main Reduce test (now alg.tst) on several dozen platforms. I am noting this now because of the expected arrival of the US\$35 + tax + p&p Raspberry Pi model B (www.raspberrypi.org/faqs) which is undoubtedly able to run Reduce, and despite its cost it will run the main test file a LOT faster than any of the systems listed in the old newsletter, and will provide more main memory than them too. You have to supply your own Keyboard and TV and hijack your mobile phone's charger and an SD card from your camera... Gosh that test ran for amound a minute on a VAX/780, almost the definitive departmental server for a proper scientific group. It is hard even to measure its time now. Arthur ```

Showing 3 results of 3