Karim Belabas on Wed, 09 May 2012 14:21:01 +0200 |
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Re: ispolygonal |
* Bill Allombert [2012-05-08 23:34]: > I am experimenting with ispolygonal: > > ? ispolygonal(36,2) > *** at top-level: ispolygonal(36,2) > *** ^----------------- > *** ispolygonal: incorrect type in ispolygonal (t_INT). > > This is confusing since 2 is a t_INT. The rationale was to avoid the e_MISC error type [ which is essentially impossible to trap cleanly ], and consider that the expected input "type" was 'a t_INT in Z_{> 2}'. This is a bit far-fetched and potentially confusing, I temporarily changed it to e_MISC. Presumably we need a general error type for "violated inequality" ? pari_err(e_INEQ, "ispolygonal", "s > 2", s); ==> incorrect value in %s (need %s). Was: %s Similar checks occur quite often, (14:13) gp > vector(-1) *** at top-level: vector(-1) *** ^---------- *** vector: incorrect type in vector [negative dimension] (t_INT). pari_err(e_INEQ, "vector", "n >= 0", n); (14:16) gp > primes(-1) *** at top-level: primes(-1) *** ^---------- *** primes: incorrect type in primes [negative dimension] (t_INT). pari_err(e_INEQ, "primes", "n >= 0", n); (14:18) gp > sigma(0) *** at top-level: sigma(0) *** ^-------- *** sigma: zero argument in an arithmetic function. pari_err(e_INEQ, "sigma", "x != 0", x); etc. > > ? [ispolygonal(36,3,&N),N] > %7 = [1,9223372036854775816] > > N is wrong obviously > > ? [ispolygonal(33496046025275818831719453356591156886^2,3,&N),N] > %19 = [1,47370562574818466718159911997304784776] > > N is wrong, it should be 47370562574818466708936539960450008968 Both of these had the same origin, and were specific to s = 3 [ which I had special-cased anyway, but not enough, thereby later treating s - 4 as an ulong ]. Fixed in master. What do people think about the function name ? Obviously, ispolygonalinteger() would be clearer but quite a bit more verbose than our usual functions. Cheers, K.B. -- Karim Belabas, IMB (UMR 5251) Tel: (+33) (0)5 40 00 26 17 Universite Bordeaux 1 Fax: (+33) (0)5 40 00 69 50 351, cours de la Liberation http://www.math.u-bordeaux1.fr/~belabas/ F-33405 Talence (France) http://pari.math.u-bordeaux1.fr/ [PARI/GP] `