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Re: All componens different

  • To: mathgroup at smc.vnet.net
  • Subject: [mg112016] Re: All componens different
  • From: Bob Hanlon <hanlonr at cox.net>
  • Date: Tue, 24 Aug 2010 06:15:53 -0400 (EDT)

d[v_] := Length[v] == Length[Union[v]]

d /@ {{1, 2, 3}, {1, 2, 1}}

{True,False}


Bob Hanlon

---- "Dr. Wolfgang Hintze" <weh at snafu.de> wrote: 

=============
Given a list v of natural numbers I'm looking for a function d[v_] that 
returns True if all components are different and False otherwise.

One solution is

d1[v_] := ! Or @@ Flatten[Table[v[[i]] == v[[k]], {i, 1, Length[v]}, 
{k, i + 1, Length[v]}]]

Can you find more efficient (and elegant) solutions?

Regards,
Wolfgang 



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