If your arrays are large (say, 10000 long) I would expect J to be better
than half the speed of C. Can you share your application?
If you have an implementation of +/ . * on double-precision floats
that's faster than J 8.06, I would be obliged if you'd send me a copy of
the source code.
Henry Rich
On 4/17/2017 5:14 PM, Michael Goodrich wrote:
This is getting interesting; I was already impressed with Js speed being only
twice as slow as the C version, and faster than the R version of the same code.
Looking forward to that 806 beta 3!
Btw I should uninstall the latest (stable) and start afresh?
Sent from my iPhone
On Apr 17, 2017, at 5:03 PM, Raul Miller <[email protected]> wrote:
I think you were surprised by
http://www.jsoftware.com/help/dictionary/special.htm
Specifically the special handling for +/ .* (which is handled at
parsing time rather than at execution time - the way you have things
arranged, the parser will not see +/ .* and hypothetically you could
arrange for sum .* in contexts where sum was defined differently).
I hope this helps,
--
Raul
On Mon, Apr 17, 2017 at 4:51 PM, Michael Goodrich
<[email protected]> wrote:
Greetings:
Got a nasty surprise today. have a non-trivial J app with the following
supporting original definitions:
sum =. +/
dot =. +/ . *
sqrd =. *:
ssq =. +/ @: sqrd
Which I changed (thinking I was being elegant) to
sum =. +/
dot =. sum . *
sqrd =. *:
ssq =. sum @: sqrd
After this change the run time increased by a factor of 5!
Insights?
----------------------------------------------------------------------
For information about J forums see http://www.jsoftware.com/forums.htm
----------------------------------------------------------------------
For information about J forums see http://www.jsoftware.com/forums.htm
----------------------------------------------------------------------
For information about J forums see http://www.jsoftware.com/forums.htm
---
This email has been checked for viruses by AVG.
http://www.avg.com
----------------------------------------------------------------------
For information about J forums see http://www.jsoftware.com/forums.htm
