In that revision Sean's log message said:
Log Message:
-----------
it'd be nice to have a bigger table or know the generator+seed that produced it
And the added comment in the file says:
+/* TODO: it'd be useful to figure out which random number generator
+ * created this table so we could create a substantially bigger one
+ * while retaining these 20x20x20 values for backwards-compatibility.
+ */
I am interested in that task and have searched extensively for the
original authors of that code to no avail so far:
Author:
------
William H. (Bill) Laut
l...@alien.gici.com
Gull Island Consultants, Inc.
Muskegon, MI 49440
Phone: (616) 780-3321
With credit to:
--------------
Tom DiGiacinto
Gull Island Consultants, Inc.
In initially analyzing the file I found a likely error and commented
on it in the code at revision 60397 begging at line 845:
/* FIXME: The following array of numbers has only 16 entries!
* Are the Remaining 4 intialized to zero? Is that
* intentional? */
{-0.299386323429644110, 0.432286161929368970,
0.484158257488161330, -0.180591955780982970,
-0.471683348063379530, 0.256541807204484940,
-0.160706320777535440, 0.273074500262737270,
0.443456499371677640, -0.255790608935058120,
-0.009335475042462349, -0.479141823947429660,
-0.254775068257004020, -0.468241036403924230,
0.069491242058575153, 0.023787757847458124},
It looks to me if there is a line of four values missing. I believe
the missing four values will result in the last four values being
initialized to zero, but that seems not to fit the rest of the data,
thus my theory of a missing line.
I note the numbers are to 18 decimal places of precision with:
min = -0.499899442773312330
max = 0.499892916996032000
so the range appears to be [-0.5 > X < +0.5], and I assume without
further analysis that the numbers are uniformly distributed.
The turb_table is used in one file (./src/liboptical/sh_wood.c) where
it is used to randomize tree ring dimensions.
I am confident I can get a similar sub-sequence of a longer stream but
maybe not an identical one. Even if not identical I'm pretty sure
some output sample targets with the two sequences would meet the
looks-good-enough-alike test.
Would such an almost-the-same sequence be acceptable?
Best regards,
-Tom
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