Re: Simplifying If expressions
- To: mathgroup at smc.vnet.net
- Subject: [mg102933] Re: Simplifying If expressions
- From: Bill Rowe <readnews at sbcglobal.net>
- Date: Wed, 2 Sep 2009 04:05:42 -0400 (EDT)
On 9/1/09 at 3:53 AM, mephi42 at gmail.com (beep.beep) wrote: >When I try to Simplify[If[x==0,x,0]] Mathematica returns >If[x==0,x,0] rather than 0. It seems that it does not take into >account that left and right if-branches should be simplified using >($Assumptions)&&if-condition and ($Assumptions)&&!if-condition >respectively. Is there a way to force that behaviour? Clearly, you must have not assigned a value to x or have a non-numeric value assigned to x when Mathematica tries to evaluate If[x==0,x,0]. Mathematica is returning this as the result because it cannot determine whether x is equal to or not. Possibly what you want is If[x===0, x, 0] This will return 0 when x has no assigned value since a symbol is not identical 0. Another possibility is If[x==0, x, 0, 0] which will return 0 if x is not equal 0 or if Mathematica cannot determine whether x is equal to zero or not. Simplify cannot correct the fundamental issue here and is not needed.