Thanks -- this one makes sense. (It is shuffles the multiplications into a balanced tree so that the top-level multiplication is the product of all the odds (<=n) times the product of the evens.)
Sympy itself uses prime swing. On Friday, May 16, 2014 9:50:57 AM UTC-7, Richard Fateman wrote: > > You are right! So sorry! I copied the wrong program into my note. > > Here is a correct version. (Again, Peter's article is fun to read...) > > (defun ff(n m) (if (<= n m) n (*(ff n (+ m m))(ff (- n m) (+ m m))))) > > For this one, (ff 10 1) computes 10! and > does the following multiplications. > > (ff 10 1) > > (* 10 2) > (* 20 6) > (* 8 4) > (* 120 32) > (* 9 1) > (* 9 5) > (* 7 3) > (* 45 21) > (* 3840 945) > > 3628800 > > The effect is far more pronounced for 100!. There are other fun hacks > though. > I hope you have the time and interest to try this on python. > RJF > > > > -- You received this message because you are subscribed to the Google Groups "sympy" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/sympy. To view this discussion on the web visit https://groups.google.com/d/msgid/sympy/ab4d192c-3be7-4a3e-9358-7e8c6e6cf0f8%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
