Re: Cases

*To*: mathgroup at smc.vnet.net*Subject*: [mg50439] Re: [mg50423] Cases*From*: "Ingolf Dahl" <ingolf.dahl at telia.com>*Date*: Sat, 4 Sep 2004 01:43:14 -0400 (EDT)*Reply-to*: <ingolf.dahl at telia.com>*Sender*: owner-wri-mathgroup at wolfram.com

Jerry, I think Not[d] is only defined if d is True or False, and it is not a pattern. Moreover, if a, b, c and d are undefined, Mathematica does not know if they are equal or not. You might test if these symbols are identical: Cases[x, y_ /; UnsameQ[y, d]] gives you {a, b, c} Ingolf Dahl Sweden -----Original Message----- From: Blimbaum, Jerry AA R22 [mailto:jerry.blimbaum at navy.mil] To: mathgroup at smc.vnet.net Subject: [mg50439] [mg50423] Cases Given: x = {a,b,c,d,d}; Applying Cases[x,d] gives an output of {a,b,c}...... However, Cases[x,Not[d]] gives as output an empty list { }... I expected {a,b,c}..... Why didnt I get that? This issue came up when using Thread on vectors...and in some cases the Thread resulted in 0 == 0 so it's output in the list was True....and I wanted to remove them.... thanks.....jerry blimbaum