Re: function IF with several equality conditions

*To*: mathgroup at smc.vnet.net*Subject*: [mg49111] Re: function IF with several equality conditions*From*: Bill Rowe <readnewsciv at earthlink.net>*Date*: Thu, 1 Jul 2004 05:26:16 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

On 6/30/04 at 5:34 AM, mbekkali at gmail.com (Mukhtar Bekkali) wrote: >I have two questions that HELP file of Mathematica does not >address: >(1) How do I implement IF with several conditions. I tried >something like this >a=1; Table[If[{x1>a,x2<a},0,1],{x1,0,2},{x2,0,2}] >and get no results. The construct {expr1, expr2 ... } is a list of expressions and doesn't have a true/false value. Change the code to read Table[If[x1>a && x2<a,0,1],{x1,0,2},{x2,0,2}] or Table[If[And@@{x1>a,x2<a},0,1],{x1,0,2},{x2,0,2}] and you will get what you want >Also, (2) IF does not accept equality conditions either, say >a=1; Table[If[x=a,0,1],{x,0,2}] The operator "=" is the assignment operator not a test for equality. You need to use "==" as in Table[If[x==a,0,1],{x,0,2}] >I am surprised that such simple things are not covered by help >file. Both of these are covered in the Mathematica Book which is included as part of the Help Browser. But since both the usage of "==" vs "=" and usage of {} to represent lists are fundamental Mathematica syntax, they are not documented again in the documentation for If. -- To reply via email subtract one hundred and four