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Re: Find position of nonzero elements

  • To: mathgroup at smc.vnet.net
  • Subject: [mg120376] Re: Find position of nonzero elements
  • From: Dominic Wörner <dominic.woerner at mpi-hd.mpg.de>
  • Date: Wed, 20 Jul 2011 06:34:22 -0400 (EDT)
  • References: <201107191053.GAA10147@smc.vnet.net> <Pine.LNX.4.63.1107190532290.28777@wopr.wolfram.com>

Thanks Oliver and also Andy. This is very good to know!

Am 19.07.2011 um 12:33 schrieb Oliver Ruebenkoenig:

> On Tue, 19 Jul 2011, Dominic W=F6rner wrote:
>
>> Hi,
>>
>> How can I find the indices i and j of all nonzero elements of a matrix.
>> I want that because there are only some nonzero elements in a huge
>> matrix.
>>
>> Best regards,
>> Dominic
>
> Dominic,
>
> how about
>
> sa = SparseArray[IdentityMatrix[4]]
> sa["Properties"]
> sa["NonzeroPositions"]
>
> Oliver
>
>>
>>



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