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

• To: mathgroup at smc.vnet.net
• Subject: [mg124358] Re: How to easily set up all coefficients to be positive in Solving an integer equation?
• From: Bob Hanlon <hanlonr357 at gmail.com>
• Date: Tue, 17 Jan 2012 03:33:12 -0500 (EST)
• Delivered-to: l-mathgroup@mail-archive0.wolfram.com

```n = 5;

var = Array[x, n];

coef = RandomInteger[{-10, 10}, n];

Solve[Flatten[{coef.var == 0, Thread[var > 0]}], var, Integers]

Bob Hanlon

On Mon, Jan 16, 2012 at 5:11 PM, 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>0 && x>0 && x>0 &&...x[n]>0`
> Is there any easy way to write such code?
>

```

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