On Wed, Feb 8, 2012 at 10:41 AM, Goswin von Brederlow <goswin-...@web.de> wrote: > [...] > Maybe the size of the hashtable indeed isn't the problem but the hash > function. Here is something odd: > > # for i = 1 to 63 do Printf.printf "%d %d\n" (1 lsl i) (Hashtbl.hash (1 lsl > i)) done;; > 2 2 > 4 4 > 8 8 > 16 16 > 32 32 > 64 64 > 128 128 > 256 256 > 512 512 > 1024 1024 > 2048 2048 > 4096 4096 > 8192 8192 > 16384 16384 > 32768 32768 > 65536 65536 > 131072 131072 > 262144 262144 > 524288 524288 > 1048576 1048576 > 2097152 2097152 > 4194304 4194304 > 8388608 8388608 > 16777216 16777216 > 33554432 33554432 > 67108864 67108864 > 134217728 134217728 > 268435456 268435456 > 536870912 536870912 > 1073741824 0 > 2147483648 0 > 4294967296 0 > 8589934592 0 > 17179869184 0 > 34359738368 0 > 68719476736 0 > 137438953472 0 > 274877906944 0 > 549755813888 0 > 1099511627776 0 > 2199023255552 0 > 4398046511104 0 > 8796093022208 0 > 17592186044416 0 > 35184372088832 0 > 70368744177664 0 > 140737488355328 0 > 281474976710656 0 > 562949953421312 0 > 1125899906842624 0 > 2251799813685248 0 > 4503599627370496 0 > 9007199254740992 0 > 18014398509481984 0 > 36028797018963968 0 > 72057594037927936 0 > 144115188075855872 0 > 288230376151711744 0 > 576460752303423488 0 > 1152921504606846976 0 > 2305843009213693952 0 > -4611686018427387904 0 > 0 0 > - : unit = () > > Is every value over a billion hashed to 0? > > MfG > Goswin >
Hi, you're making it look worse than it really is: $ ocaml Objective Caml version 3.12.0 # Hashtbl.hash 1000000001;; - : int = 1000000001 # Hashtbl.hash 1073741824;; - : int = 0 # Hashtbl.hash 1073741825;; - : int = 1 # Hashtbl.hash 1073741826;; - : int = 2 # Hashtbl.hash 1073741829;; - : int = 5 # Hashtbl.hash 1073741830;; - : int = 6 # Hashtbl.hash 9007199254740994;; - : int = 2 # Hashtbl.hash 9007199254740990;; - : int = 1073741822 Cheers, -- Philippe Wang m...@philippewang.info -- Caml-list mailing list. Subscription management and archives: https://sympa-roc.inria.fr/wws/info/caml-list Beginner's list: http://groups.yahoo.com/group/ocaml_beginners Bug reports: http://caml.inria.fr/bin/caml-bugs