Re: [fricas-devel] Re: [BUG] r1976: Remove argumentless 'random'; pfo.spad
Another integral affected by this change: (1) -> integrate(1/sqrt(1 + b*sec(x))^3,x) >> Error detected within library code: RadicalFunctionField: curve is not irreducible It worked in 1.2.7. A simple change can make most of these problems go away, but as discussed before, there's a better solution. diff --git a/src/algebra/pfo.spad b/src/algebra/pfo.spad index 816fe22..5904fee 100644 --- a/src/algebra/pfo.spad +++ b/src/algebra/pfo.spad @@ -235,7 +235,7 @@ FunctionSpaceReduce(R, F) : Exports == Implementation where K2Z : K -> F redmap := table()$AssociationList(K, Z) -nn : Integer := 1 +nn : Integer := 10^6 newReduc(n) == nn := n -- You received this message because you are subscribed to the Google Groups "FriCAS - computer algebra system" group. To unsubscribe from this group and stop receiving emails from it, send an email to fricas-devel+unsubscr...@googlegroups.com. To post to this group, send email to fricas-devel@googlegroups.com. Visit this group at https://groups.google.com/group/fricas-devel. For more options, visit https://groups.google.com/d/optout.
Re: [fricas-devel] Re: [BUG] r1976: Remove argumentless 'random'; pfo.spad
Another integral with exact same problem: (1) -> integrate((k*x^2 - 1)/((a*k*x + b)*(b*x + a)*sqrt((1 - x^2)*(1 - k^2*x^2))), x) >> Error detected within library code: catdef: division by zero Under FriCAS 1.2.7, this integral returns after 1 minute. -- You received this message because you are subscribed to the Google Groups "FriCAS - computer algebra system" group. To unsubscribe from this group and stop receiving emails from it, send an email to fricas-devel+unsubscr...@googlegroups.com. To post to this group, send email to fricas-devel@googlegroups.com. Visit this group at https://groups.google.com/group/fricas-devel. For more options, visit https://groups.google.com/d/optout.
Re: [fricas-devel] Re: [BUG] r1976: Remove argumentless 'random'; pfo.spad
> AFAICS code using FSRED has design problem: due to random > choice we may reduce denominator to 0. I believe that > in such case we should restart computations using different > reduction. But current code just signals error (which is > definitely wrong). Yes, that should be the correct solution. > Computations with divisors may be quite heavy and take very > long time (days, months and possibly years). It may also > need substantial memory, so after long computation you > may funally run out of memory. The problem is that if a=1, this integral can be computed in seconds, I though replace the constant numerator with a symbol should not make it takes much longer time. -- You received this message because you are subscribed to the Google Groups "FriCAS - computer algebra system" group. To unsubscribe from this group and stop receiving emails from it, send an email to fricas-devel+unsubscr...@googlegroups.com. To post to this group, send email to fricas-devel@googlegroups.com. Visit this group at https://groups.google.com/group/fricas-devel. For more options, visit https://groups.google.com/d/optout.
Re: [fricas-devel] Re: [BUG] r1976: Remove argumentless 'random'; pfo.spad
> > > 1) The default value for nn is incorrect, and nn is not > > updated after being used in K2Z. > > > > Actually, I think argumentless 'random' is a good idea. > > I misunderstood a little, my point is: > 1) The default value of nn should not be 1. > 2) We should use "1+random(nn)" in this case to avoid 0. In general we may have something like '1/(x + k)' where 'k' is arbitrary integer. So you can not avoid zero denominator by adding some bias. In other words: you may reduce probablity of zero denominator but you can not elimintate it. To deal with zeros we need to handle failing reduction (restart computation). -- Waldek Hebisch -- You received this message because you are subscribed to the Google Groups "FriCAS - computer algebra system" group. To unsubscribe from this group and stop receiving emails from it, send an email to fricas-devel+unsubscr...@googlegroups.com. To post to this group, send email to fricas-devel@googlegroups.com. Visit this group at https://groups.google.com/group/fricas-devel. For more options, visit https://groups.google.com/d/optout.
