Using -: in that context requires extra parens. Besides, ←→ is prettier.
On Fri, Dec 26, 2014 at 8:52 AM, R.E. Boss <r.e.b...@outlook.com> wrote: > > Why not use the primitive '-:' ? > > (+/(1+i._)^-s) -: */%1-(p:i._)^-s > > > R.E. Boss > > > > -----Original Message----- > > From: programming-boun...@forums.jsoftware.com [mailto:programming- > > boun...@forums.jsoftware.com] On Behalf Of Roger Hui > > Sent: vrijdag 26 december 2014 17:28 > > To: Programming forum > > Subject: Re: [Jprogramming] "Such that" syntax in J > > > > ←→ are metasymbols, commonly used in mathematics to denote > > equivalence. > > > > > > > > On Fri, Dec 26, 2014 at 8:20 AM, Jon Hough <jgho...@outlook.com> 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: rogerhui.can...@gmail.com > > > > To: programm...@jsoftware.com > > > > 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 <jgho...@outlook.com> > > 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 > ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
