Raul indeed i can make up anything using various b. storing seems to be reliable only as 8b characters i think some 16b Unicode's are illegal so i cannot store and manipulate 16 bit floats that way to do 12b floats i might store pairs in 3 bytes
i suppose one could communicate with the many DLL's that access the BFloat16 hiding in every AVX machine by sifting in and out of that format though bytes are rather inconvenient due to the vagaries of how sign, multiplier and multiplicand bits are stored one would prefer that that was all handled and could check for positivity with a simple >0 rather than make a DLL call or another sift ~greg heil https//picsrp.github.io -- from: Raul Miller <[email protected]> to: Programming forum <[email protected]> date: Aug 2, 2021, 10:12 PM subject: Re: [Jprogramming] Two implementation questions https://www.jsoftware.com/help/dictionary/dbdotn.htm #~.(i.1024) 32 b. 1 64 >Or, on my machine, the bitwise operations give me 64 bits packed in a J atom. >Constructing mechanisms which make an array of such things appear to be a bit >array of arbitrary dimensions should be straightforward for someone with your >background. (Though you could also use them "as is" with an implicit trailing >dimension of 64.) Thanks, -- Raul -- from: greg heil <[email protected]> to: Programming forum <[email protected]> date: Aug 2, 2021, 8:33 PM subject: Re: [Jprogramming] Two implementation questions Henry Hmm, how would one create an array of bits? use packed 8-bit characters? would one use a similar strategy for 16-bit floats? (which i am more interested in, and is directly supported in most hardware -for its utility in Deep Learning) Seems a serious amount of packing unpacking indexing chopping and inverting just for matrix multiplication i could be wrong but i do not see the algorithm ~greg heil https//picsrp.github.io -- from: Henry Rich <[email protected]> to: [email protected] date: Aug 2, 2021, 8:07 PM subject: Re: [Jprogramming] Two implementation questions >Rather than having a new datatype, you could create arrays of bits and use >bitwise booleans on them. >Can you list a set of operations on bit arrays that would suffice to solve the >problems you were working on? Henry Rich -- from: greg heil <[email protected]> to: Programming forum <[email protected]> date: Aug 2, 2021, 7:07 PM subject: Re: [Jprogramming] Two implementation questions i did my undergraduate and doctoral thesis on the categories of Graphs with multiplication (and/or) as the operator both were done using APL's bit-boolean's much more than just multiplication were done on these graphs homomorphism, isomorphism clustering cliquing transitive/closures all benefited from the simpler bit-boolean's as categories of graphs run the full gamut from 0-100% full one cannot use any form of linked list a size multiplication by 8 would (at least in those days) have caused a LOT of cache misses even now caching would be a lot happier because the Social Networks under investigation (the object of the studies) have grown a LOT bigger!-) ~greg heil https//picsrp.github.io . ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
