Horror matrices for iterative methods

Jabberwocky, by Lewis Carroll.		Horror Matrices for Iterative Methods by T. D.
'Twas brillig, and the slithy toves Did gyre and gimble in the wabe; All mimsy were the borogoves, And the mome raths outgrabe. 'Beware the Jabberwock, my son! The jaws that bite, the claws that catch! Beware the Jubjub bird, and shun The frumious Bandersnatch!' He took his vorpal sword in hand: Long time the manxome foe he sought-- So rested he by the Tumtum tree, And stood awhile in thought. And as in uffish thought he stood, The Jabberwock, with eyes of flame, Came whiffling through the tulgey wood, And burbled as it came! One, two! One, two! And through and through The vorpal blade went snicker-snack! He left it dead, and with its head He went galumphing back. 'And hast thou slain the Jabberwock? Come to my arms, my beamish boy! O frabjous day! Callooh! Callay!' He chortled in his joy. 'Twas brillig, and the slithy toves Did gyre and gimble in the wabe; All mimsy were the borogoves, And the mome raths outgrabe.		`Twas normig, and the A 2-norms Did tire and scale in conjugate: All flimsy were the direct codes, And matrices outgave. "Beware the 'OrrorMat, my son! The Poisson teeth, the scales of ill! Beware the Netlib blurb; don't lose Orthogonality!" With Matvec at his right-hand side, (or Hamlet, say?) he SPAI'd him fast -- My tale cannot end, he thought, just Converge to stanza last. Yet, in while(epsilon) he waits, Came 'OrrorMat, with random eigs, Descending steeply through N-space, in lost normality! One, two! One, two! And through and through The Matvec blade went snicker-snack! At low resid, and with its x He went Galerkin' back. "And hast converged the 'OrrorMat? Residual eps, my GMRES! Don't kry, luv! tril(U)! tril(A)!" He came at last to rest. `Twas normig, and the A 2-norms Did tire and scale in conjugate: All flimsy were the direct codes, And matrices outgave.

  "Normig" is a Middle Saxon term, no longer in use, which is the time of day when well-behaved matrices all come out to take their norm (about noon, or a little after). See also a glossary.

Copyright 2006, Tim Davis. Please don't copy-and-paste or hot-link this poem without permission; link to this page instead: http://www.cise.ufl.edu/~davis/Poetry/horror_iterative.html

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