That wouldn't make a lot of sense, though, for classic operations on sparse matrices (like +/ .*), would it?
That said, it might sense to leave 0 as the sparse element, and then use the distinction between sparse zeros and dense zeros to track undefined values... Thanks, -- Raul On Wed, Sep 20, 2017 at 6:56 PM, Don Guinn <[email protected]> wrote: > I thought that possibly sparse matrices might be a way to handle missing > values, particularly if there a lot of undefined values. But couldn't > figure out how to specify the sparse element to be _. . > > On Wed, Sep 20, 2017 at 3:22 PM, Henry Rich <[email protected]> wrote: > >> No; see >> >> http://code.jsoftware.com/wiki/Vocabulary/under Details >> >> http://code.jsoftware.com/wiki/Vocabulary/percent#dyadic Details >> >> It would perhaps be better if 0 * _5 gave -0, but it doesn't. The other >> deviations are improvements added by J. >> >> Henry Rich >> >> On Wed, Sep 20, 2017 at 10:51 AM, Erling Hellenäs < >> [email protected]> >> wrote: >> >> > Hi all ! >> > >> > Here is part of the standard. Required exception handling. Things I >> > discuss in my post. Is it implemented in J? >> https://en.wikipedia.org/wiki/ >> > IEEE_754#Exception_handling >> > The floating point standard is obviously used in environments where the >> > users can not afford random results, so there must be solutions to the >> > problems I mention, which we also can see in this wikipedia article. >> > >> > Cheers, >> > Erling >> > >> > >> > Den 2017-09-20 kl. 16:27, skrev Erling Hellenäs: >> > >> >> I hope others want to read my post even if Raul discards it as not >> worthy >> >> of comments. /Erling >> >> >> >> >> >> Den 2017-09-20 kl. 12:25, skrev Raul Miller: >> >> >> >>> This isn't just J - this is the IEEE-754 floating point standard. >> >>> >> >>> It would be really nice if computers could deal with infinities, >> >>> instantly, at no cost. Sadly, though, that's not going to happen. >> >>> >> >>> FYI, >> >>> >> >>> >> >> ---------------------------------------------------------------------- >> >> 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 >> > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
