There's a simple verb to display the internal representation of a object at the end of the essay on J's internal representation at https://code.jsoftware.com/wiki/User:Devon_McCormick/Data/JInternalRepresentation .
On Thu, Jan 30, 2020 at 6:28 PM Raul Miller <[email protected]> wrote: > 3!:3 y gives you a hex dump of y, including the array header. > > So, for example, you could inspect a "boolean" array for yourself: > 3!:3]1 p: i.99 > > Or: the "boolean" array type is represented as C bytes. > > (This is because bits are not addressable and for typical cases the > consequence of a packed bit representation would be a significant > performance penalty. Similarly, lapack can offer significant speed > improvements in some cases which are difficult for the interpreter to > identify speedily.) > > (That said, note also that "boolean" is a term which has gone > significant linguistic drift. As a consequence, boolean operations, > such as *. or +. (which are faithful to the original concept) do not > necessarily produce what most people with computer or math training > understand as boolean results.) > > Thanks, > > -- > Raul > > On Thu, Jan 30, 2020 at 4:28 PM 'Sergey Kamenev' via Programming > <[email protected]> wrote: > > > > Hi! > > > > I read https://code.jsoftware.com/wiki/System/ReleaseNotes/J901. > > > > It says about improving the performance of Boolean arrays. > > Is it due to the fact that it is stored in memory as bits, or as bytes, > or still as integers? > > > > Sergey. > > ---------------------------------------------------------------------- > > For information about J forums see http://www.jsoftware.com/forums.htm > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm > -- Devon McCormick, CFA Quantitative Consultant ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
