determinant of sparse matrix

• Subject: determinant of sparse matrix
• From: Stavros Macrakis
• Date: Wed, 14 Mar 2007 13:49:37 -0400

Yes, some of the default algorithms do very poorly:

  determinant(ident(12)) =>  0.17 seconds
  determinant(ident(13)) =>  0.65 seconds
  determinant(ident(14)) =>  3.07 seconds
  determinant(ident(15)) => 21.06 seconds

even though full matrix inversion is fast for much larger matrices:

  ident(500)^^-1$ =>         2.11 seconds

I can confirm that ratmx helps in this case:

   determinant(ident(100)), ratmx:true => 1.01 seconds

Let us know more about your problem if ratmx doesn't help....

          -s

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