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Is there a lowest Eigenvalues function around?

• To: mathgroup@smc.vnet.net
• Subject: [mg10988] Is there a lowest Eigenvalues function around?
• From: "Christopher R. Carlen" <crobc@epix.net>
• Date: Mon, 16 Feb 1998 03:39:55 -0500
• Organization: epix Internet Services

I have to find the eigenvalues of very large matrices, ie 1024x1024 up
to over 10000x10000 .  I run out of memory when trying to do more than
about 1600x1600 .  I know there are algorithms to find the lowest or
highest eigenvalues of a matrix, but the Mathematica function
Eigenvalues[] finds all of them.  

Does anyone know if there is an implementation of a lowest-eigenvalues
function anywhere?  I have looked aroung at www.wolfram.com but didn't
find anything.

Also, I wonder about memory usage in storing matrices.  If a matrix is
sparse, does it require less memory to store and manipulate than a
not-sparse matrix?  Does a matrix with only real values require less
memory than a complex matrix?


Thanks.
-- 
_______________________
Christopher R. Carlen
crobc@epix.net          <--- Reply here, please. carlenc@cs.moravian.edu
My OS is Linux v2