Re: rules on vector sequence

*To*: mathgroup at smc.vnet.net*Subject*: [mg98061] Re: rules on vector sequence*From*: "Sjoerd C. de Vries" <sjoerd.c.devries at gmail.com>*Date*: Sun, 29 Mar 2009 02:44:49 -0500 (EST)*References*: <gqkurj$47q$1@smc.vnet.net>

Filippo, Generate all possible vectors with Tuples then select (with Cases or Select) the ones that comply with 2 and 3. Use Total for 2 and Count for 3. Cheers -- Sjoerd On Mar 28, 12:40 pm, Filippo Miatto <sottosupr... at gmail.com> wrote: > Dear all, > I need to generate all the vectors, of a given length N, that have > these three properties: > > 1- the entries have to be among -2,-1,0,1,2 > 2- the sum of all the entries has to be 0 > 3- only two or four of the entries can be different from 0 > > do you have any suggestions on how i can do that? i tried something > but without success.. expecially i don't know how to implement the > third rule.. > thank you in advance! > Filippo