Now it sounds like you want: (#~ g) x Assuming, of course, that x and g are appropriate.
I hope this helps, -- Raul On Fri, Dec 26, 2014 at 11:20 AM, Jon Hough <[email protected]> wrote: > Thanks for replying. > > I'm confused about two things. > > (1) I'm worried I haven't explained myself well. > I mean I want to find all x given g(x) is true for some function g. > > i.e. the set { x | g(x) is true } > (You may have answered this, I need to read your example more carefully, but > this leads me to problem 2...) > > (2) I don't understand what > ←→ > means in terms of J. These are not ASCII characters or J primitives. > > Thanks. > >> Date: Fri, 26 Dec 2014 08:13:40 -0800 >> From: [email protected] >> To: [email protected] >> Subject: Re: [Jprogramming] "Such that" syntax in J >> >> f x >> >> where x is an array of all values of interest. For (countably) infinite >> sets you have to express x in terms of i._ . For example, to express the >> Euler product formula for the Riemann zeta function, >> >> +/(1+i._)^-s ←→ */%1-(p:i._)^-s >> >> >> >> On Fri, Dec 26, 2014 at 8:04 AM, Jon Hough <[email protected]> wrote: >> > >> > In Haskell (and other languages I'm sure) one can express the idea of >> > "such that" to denote one expression depending on another. In Haskell we >> > can use the syntax: >> > >> > [ f x | x <- xs ] >> > >> > which means >> > "the list of all f x >> > such that x is drawn from xs." >> > >> > So | is syntactically similar to the English "such that". (and very much >> > like | in mathematical sets) >> > >> > I would like to know if J has a construct to express the above Haskell >> > code. >> > >> > Thanks, >> > Jon. >> > >> > ---------------------------------------------------------------------- >> > 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
