Re: Is there way to use something like Assuming with the function SIgn?

*To*: mathgroup at smc.vnet.net*Subject*: [mg128776] Re: Is there way to use something like Assuming with the function SIgn?*From*: "Eduardo M. A. M. Mendes" <emammendes at hotmail.com>*Date*: Sat, 24 Nov 2012 02:30:47 -0500 (EST)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*Delivered-to*: l-mathgroup@wolfram.com*Delivered-to*: mathgroup-newout@smc.vnet.net*Delivered-to*: mathgroup-newsend@smc.vnet.net*References*: <20121123082533.A76536891@smc.vnet.net> <CAEtRDScjm0mpXcwfkuKfASSTUQUuN3DKeXCYJuOZNCehFKRw7A@mail.gmail.com>

Hello Many thanks. Ed On Nov 23, 2012, at 12:01 PM, Bob Hanlon <hanlonr357 at gmail.com> wrote: > "Assuming[assum, expr] evaluates expr with assum appended to > $Assumptions, so that assum is included in the default assumptions > used by functions such as Refine, Simplify, and Integrate." > > list = {1, -2, a, 3}; > > Assuming[a < 0, Simplify[Sign[list]]] > > {1, -1, -1, 1} > > However, more compactly > > Simplify[Sign[list], a < 0] > > {1, -1, -1, 1} > > > Bob Hanlon > > > On Fri, Nov 23, 2012 at 3:25 AM, Eduardo Mendes <emammendes at hotmail.com> wrote: >> Hello >> >> I was wondering there is something similar to what can be done with Integrate, Reduce and Limit. Something like >> >> list={1,-2,a,3} >> >> Assuming[a<0,Sign[list]] >> >> Mathematica returns {1,-1,Sign[a],1} and I would like to see something like {1,-1,-1,1}. Can that be done? >> >> Many thanks >> >> Ed >> >> >

**References**:**Is there way to use something like Assuming with the function SIgn?***From:*Eduardo Mendes <emammendes@hotmail.com>