Re: Learning recursion with hailstone seqence

"DAVID B MORGAN" <lepton2@xxxxxxxxxxx> schreef in bericht
news:J%47h.3638$v93.2468@xxxxxxxxxxx
I'm playing with the hailstone sequence. My function will
need to iterate millions of times to process the data. I have two
questions:

1. Can this function be optimised ? (approx 2^67 iterations are neccessary
on current dataset)
2. How can I test huge numbers (like 2^1000) --- Int64 can't handle it

function hailstone(x:int64):int64;
begin
if odd(x) then result:=x*3+1
else result:=x shr 1;
if result<>1 then hailstone(result) ;
end;


If the purpose is to exercise with recursion, then consider this function
instead:

function hailstone(x:int64):int64;
// will return iteration length
begin
if odd(x) then x:=x*3+1 else x:=x shr 1;
if x>1 then result:=1+hailstone(x) else result:=0;
end;

Count on a recursion depth of 50 times the bit-length of x.
Tom


.

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