Interesting, but why? Just adding integers apply is faster than tree_reduce.
Are there general guide-lines when to use what?
Oliver
On Mon, Dec 27, 2010 at 02:42:10PM -0600, Barton Willis wrote:
> Mostly unrelated: changing apply("+", ...) to tree_reduce("+",...) speeds up one of your
> calculations by a factor of about 85 (37 seconds to 0.44 seconds) and doesn't change
> the order the floats are added:
>
> (%i13) testf1(n) := float(apply("+",makelist(log(i)*(-1)^i,i,1,n)));
> Evaluation took 0.0000 seconds (0.0000 elapsed)
> (%o13) testf1(n):=float(apply("+",makelist(log(i)*(-1)^i,i,1,n)))
>
> (%i20) testf2(n) := float(tree_reduce("+",create_list(log(i)*(-1)^i,i,1,n)));
> Evaluation took 0.0000 seconds (0.0000 elapsed)
>
> (%o20) testf2(n):=float(tree_reduce("+",create_list(log(i)*(-1)^i,i,1,n)))
> (%i22) testf1(10000);
> Evaluation took 37.1600 seconds (37.1600 elapsed)
> (%o22) 4.83098653863282
>
> (%i23) testf2(10000);
> Evaluation took 0.4300 seconds (0.4300 elapsed)
> (%o23) 4.83098653863282
>
> Sorry for the off-topic shameless plug (for tree_reduce).
>
> --Barton
>
> -----maxima-bounces at math.utexas.edu wrote: -----
>
> >testf1(n)?:=?float(apply("+",create_list(log(i)*(-1)^i,i,1,n)));
> >testf1c(n):=block([fpprec:30],bfloat(apply("+",create_list(log(i)*(-1)^i,i
> >,1,n))));
> >testf1f(n)?:=?apply("+",create_list(float(log(i))*(-1)^i,i,1,n));
> >
> >21:
> >
> >(%i24)?testf1(10000);
> >Evaluation?took?79.0520?seconds?(125.7410?elapsed)