I was fiddling with patterns in the first 10e9 digits of Pi this evening and
was surprised by a timing.
Rather than what I was fooling with, I put it into a smaller easily reproduced
example, to wit -
MBpro-3:JKTststs jkt$ ja
JVERSION
Engine: j807/j64/darwin
Release-e: commercial/2019-11-04T12:57:58
Library: 8.07.26
Platform: Darwin 64
Installer: J807 install
InstallPath: /applications/j64-807
Contact: www.jsoftware.com
20?.@$ 2
0 1 0 1 1 0 0 1 1 1 0 0 0 0 1 0 0 0 1 0
rl
[: #;.1~ 1 , 2 ~:/\ ]
rl 20?.@$ 2
1 1 1 2 2 3 4 1 3 1 1
q=. (50e6 ?.@$ 10){'0123456789'
timex 'z=. rl q'
1.720735 649991296
hist
~. ,: #/.~
hist z
1 3 2 4 5 7 6 8 9
40500537 405764 4048327 40574 4095 35 410 4 1
NB. i.e. one run of 9 digits, 4 of length 8 etc.
timex 'hist z'
0.295335 536872960
exit 0
MBpro-3:JKTststs jkt$ jb
JVERSION
Engine: j901/j64avx2/darwin
Release-c: commercial/2020-01-11T12:24:26
Library: 9.01.18
Platform: Darwin 64
Installer: J901 install
InstallPath: /applications/j901
Contact: www.jsoftware.com
q=. (50e6 ?.@$ 10){'0123456789'
timex 'z=. rl q'
6.56145 649995392
hist z
1 3 2 4 5 7 6 8 9
40500537 405764 4048327 40574 4095 35 410 4 1
6.56145 % 1.720735
3.813167048
exit 0
MBpro-3:JKTststs jkt$
What surprised me was that the run length function rl took more space and about
4 times as long in J9.01 as in J8.07 - most things I try are the other way
around.
Have others had similar experiences?
Does anyone see a reason my run length verb should bog down?
- joey
----------------------------------------------------------------------
For information about J forums see http://www.jsoftware.com/forums.htm
