Oh, I see now. I thought they were J symbols. Apologies.
> Date: Fri, 26 Dec 2014 08:28:25 -0800
> From: rogerhui.can...@gmail.com
> To: programm...@jsoftware.com
> 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.
> > > >
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> > > >
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> >
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