Re: How to easily set up all coefficients to be positive in Solving an integer equation?

• To: mathgroup at smc.vnet.net
• Subject: [mg124335] Re: How to easily set up all coefficients to be positive in Solving an integer equation?
• From: DrMajorBob <btreat1 at austin.rr.com>
• Date: Tue, 17 Jan 2012 03:25:12 -0500 (EST)
• Delivered-to: l-mathgroup@mail-archive0.wolfram.com

```Either of these should work (if n is known, e.g. 10):

{x[1] > 0, x[2] > 0, x[3] > 0, x[4] > 0, x[5] > 0, x[6] > 0, x[7] > 0,
x[8] > 0, x[9] > 0, x[10] > 0}

And @@ Thread[Array[x, 10] > 0]

x[1] > 0 && x[2] > 0 && x[3] > 0 && x[4] > 0 && x[5] > 0 && x[6] > 0 &&
x[7] > 0 && x[8] > 0 && x[9] > 0 && x[10] > 0

If n is NOT known, nothing will work.

Bobby

On Mon, 16 Jan 2012 16:11:13 -0600, Rex <aoirex at gmail.com> wrote:

> Given a vector `A==[a_1, a_2, a_3,...,a_n]`, where a_i are integers,
> now
> solving an equation
> `=E2=88=91a_i * x_i==0` with all x_i>==0, and x_i to be integers.
>
> We can write some code like this
> `Solve[A . Table[x[i], {i, n}] ==  0 && Table[x[i] > 0, {i, n}],
> Integers]`
>
> But the conditions above `Table[x[i] > 0` is not rightly coded. That
> should be
> `x[1]>0 && x[2]>0 && x[3]>0 &&...x[n]>0`
> Is there any easy way to write such code?
>

--
DrMajorBob at yahoo.com

```

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