#~g seems to work. (Much neater than my code) e.g. for my prime set
g =: 1&p: (#~g) i. 100 gives what I want. So I suppose an adverb of the form #~u for verb u is close to "such that"? > From: [email protected] > Date: Fri, 26 Dec 2014 11:25:13 -0500 > To: [email protected] > Subject: Re: [Jprogramming] "Such that" syntax in J > > 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 ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
