My guess, looking at those numbers, but not mustering enough interest to plow through the video, is that by IEEE-754, he meant 32 bit IEEE-754, but J uses 64 bit IEEE-754.
I'm having trouble mustering up interest because while focusing on specific cases is useful for working with simple algorithms, for something like this you really need to be considering much larger fields of values. And I'm not going to see anything like that in this video. -- Raul On Thu, Feb 9, 2017 at 10:51 AM, Raul Miller <[email protected]> wrote: > Does this answer your question? > > a=.3.2e7 1 _1 8.0e7 > b=. 4.0e7 1 _1 _1.6e7 > a +/ .* b > 2 > (a +/ .* b) - 2 > 0 > mm=: +/@(*"1 _) > a mm b > 2 > (a mm b) - 2 > 0 > > Thanks, > > -- > Raul > > On Thu, Feb 9, 2017 at 10:44 AM, William Tanksley, Jr > <[email protected]> wrote: >> I'd be curious about whether J is automatically using one of the matrix >> multiplication algorithms that avoid the problem. >> >> On Thu, Feb 9, 2017 at 7:26 AM Skip Cave <[email protected]> wrote: >> >>> I posted the results Brian & Robert got from Gustafson's matrix multiply >>> example in J and APL to the Unum Computing forum on Google Groups >>> <https://groups.google.com/forum/#!forum/unum-computing>. Gustafson >>> occasionally posts on that group. We'll see what he says. >>> >>> Skip Cave >>> Cave Consulting LLC >>> ---------------------------------------------------------------------- >>> 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
