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

*To*: mathgroup at smc.vnet.net*Subject*: [mg128764] Re: Is there way to use something like Assuming with the function SIgn?*From*: Bill Rowe <readnews at sbcglobal.net>*Date*: Sat, 24 Nov 2012 02:26:46 -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

On 11/23/12 at 3:25 AM, emammendes at hotmail.com (Eduardo Mendes) wrote: >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? Assuming only affects the operation of a few functions in Mathematica such as Simplify. So, In[19]:= Clear[a]; list = {1, -2, a, 3}; Assuming[a < 0, Simplify[Sign[list]]] Out[21]= {1,-1,-1,1}