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Tests Performed on the Banded Singular Value Decomposition Routines

Testing the reduction of a general 3#3-by-4#4 band matrix A to bidiagonal form is done in the following stages:

  1. 16#16 is factored as 492#492, where 64#64 and 73#73 are orthogonal and 97#97 is upper bidiagonal.

  2. A given matrix C is overwritten with 64#64285#28567#67.

For each pair of matrix dimensions 499#499 and each selected matrix type, an 3#3-by-4#4 matrix 16#16 and an 3#3-by-500#500 matrix 67#67 are generated. The problem dimensions are as follows

16#16 3#3-by-4#4
64#64 3#3-by-501#501 (but 3#3-by-3#3 if nrhs 502#502 0)
73#73 501#501-by-4#4
97#97 501#501-by-501#501
67#67 3#3-by-500#500
where 505#505.

To check these calculations, the following test ratios are computed:

512#512



Susan Blackford 2001-08-13