Re: How to ±

*To*: mathgroup at smc.vnet.net*Subject*: [mg103704] Re: How to ±*From*: David Bailey <dave at removedbailey.co.uk>*Date*: Sat, 3 Oct 2009 09:01:57 -0400 (EDT)*References*: <ha243r$p76$1@smc.vnet.net> <ha4rkg$dcl$1@smc.vnet.net>

olliH wrote: > When I do it like this: > > x + ({1, -1}*5)^2 > > I get two solutions: > > {25 + x, 25 + x} > > For my problem I'm looking for a real +- Operator not a List > As people have said, this operator can be defined as you wish, but you need to be clear as to what you want it to do! Even the meaning needs careful definition. For example, do you want x +-5 to mean x+5 or x-5, or are you implicitly referring to a distribution (e.g. normal or uniform) - i.e. do you mean it in the statistical sense. David Bailey http://www.dbaileyconsultancy.co.uk