Index of /research/sparse/mat/JGD_Trefethen

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 Parent Directory        02-Nov-2009 14:42      -  
 Trefethen_150.mat       11-Nov-2008 15:08     4k  
 Trefethen_20.mat        11-Nov-2008 15:07     1k  
 Trefethen_200.mat       11-Nov-2008 15:08     6k  
 Trefethen_2000.mat      11-Nov-2008 15:12    75k  
 Trefethen_20000.mat     13-Oct-2008 17:26  1017k  
 Trefethen_20000b.mat    11-Nov-2008 15:16  1018k  
 Trefethen_200b.mat      11-Nov-2008 15:08     6k  
 Trefethen_20b.mat       11-Nov-2008 15:07     1k  
 Trefethen_300.mat       11-Nov-2008 15:09     9k  
 Trefethen_500.mat       11-Nov-2008 15:10    15k  
 Trefethen_700.mat       11-Nov-2008 15:11    23k  

Diagonal matrices with primes, Nick Trefethen, Oxford Univ.
From Jean-Guillaume Dumas' Sparse Integer Matrix Collection,
http://ljk.imag.fr/membres/Jean-Guillaume.Dumas/simc.html

Problem 7 of the Hundred-dollar, Hundred-digit Challenge Problems,
SIAM News, vol 35, no. 1.

7. Let A be the 20,000 x 20,000 matrix whose entries are zero
everywhere except for the primes 2, 3, 5, 7, . . . , 224737 along the
main diagonal and the number 1 in all the positions A(i,j) with
|i-j| = 1,2,4,8, . . . ,16384.  What is the (1,1) entry of inv(A)?

http://www.siam.org/news/news.php?id=388