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): 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} 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