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Re: Compact formulation of array of constraints

  • To: mathgroup at smc.vnet.net
  • Subject: [mg132221] Re: Compact formulation of array of constraints
  • From: Bob Hanlon <hanlonr357 at gmail.com>
  • Date: Mon, 20 Jan 2014 03:59:24 -0500 (EST)
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With "patterns":


expr = Sqrt[x[2]^2] + Sqrt[x[3]^2];


Assuming[Thread[Cases[Variables[expr], x[_]] > 0], Simplify[expr]]


x[2] + x[3]


Assuming[Cases[Variables[expr], x[n_] -> (x[n] > 0)], Simplify[expr]]


x[2] + x[3]



Bob Hanlon


On Sun, Jan 19, 2014 at 2:55 AM, Yi Wang <tririverwangyi at gmail.com> wrote:

> For this example, yo can do
>
> Apply[And, (x[#] >= 0) & /@ Range[5]]
>
> For example,
>
> Assuming[(x[#] >= 0) & /@ Range[5], Simplify[Sqrt[x[2]^2]]]
>
> On the other hand, AFAIK patterns do not work in this situation.
>
> > Dear All,
> >
> >
> >
> > How can one formulate the set of constraints
> >
> >
> >
> > x[1] >= 0, x[1] >= 0, x[2] >= 0, x[3] >= 0, x[4] >= 0, x[5] >= 0
> >
> >
> >
> > by using a compact form?
> >
> >
> >
> > Thanks in advance,
> >
> >
> >
> > Paul
>
>




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