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Thread Subject:
memory blowout in sparse matrices

Subject: memory blowout in sparse matrices

From: Rich

Date: 12 Feb, 2009 16:03:02

Message: 1 of 1

Hi all,
I'm working with some sparse matrices, and am getting large memory usage depending on the row ordering of the matrix.

I'm aware that matlab has memory differences depending on whether it a sparse matrix is transposed or not, but this is a different matter.

I'm simply getting about a n factor increase in memory usage when i flip upside down (flipud) a sparse matrix, where n is the number of rows in the sparse matrix.

eg>from 'whos'
  Name Size Bytes Class Attributes

  tmp 1000x22842 123628 double sparse
  tmp1 1000x22842 157485856 double sparse

where tmp1=flipud(tmp)

Is there a reason for this? If I understand the reason, it might help cicurmvent the issue arising again.

thanks
Richard

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