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Re: All componens different

  • To: mathgroup at smc.vnet.net
  • Subject: [mg112002] Re: All componens different
  • From: David Carraher <david_carraher at terc.edu>
  • Date: Tue, 24 Aug 2010 06:13:18 -0400 (EDT)

Hi Wolfgang,

How about this ...?

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

If you want to verify that the list consists of natural numbers, you'll 
have to put in that constraint in your definition of v.

Best regards,

David Carraher


*****

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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