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Re: Find position of nonzero elements

• To: mathgroup at smc.vnet.net
• Subject: [mg120357] Re: Find position of nonzero elements
• From: Oliver Ruebenkoenig <ruebenko at wolfram.com>
• Date: Wed, 20 Jul 2011 06:30:57 -0400 (EDT)
• References: <201107191053.GAA10147@smc.vnet.net>

On Tue, 19 Jul 2011, Dominic Wörner 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

>
>

• References:
  • Find position of nonzero elements
    • From: Dominic Wörner <dominic.woerner@mpi-hd.mpg.de>