1lis_array_qr(3f)             Lis Library Functions            lis_array_qr(3f)
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NAME

6       lis_array_qr - calculate the eigenvalues with the QR algorithm
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SYNOPSIS

10       subroutine lis_array_cgs(LIS_INTEGER n, LIS_SCALAR a(), LIS_SCALAR q(),
11       LIS_SCALAR  r(),  LIS_INTEGER  qriter,  LIS_SCALAR  qrerr,  LIS_INTEGER
12       ierr);
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DESCRIPTION

16       Calculate the eigenvalues of matrix A with the QR algorithm.
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INPUT

20       n      The size of the matrices
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23       a      The array that stores matrix A of size n * n
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26       q      The work array Q of size n * n
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29       r      The work array R of size n * n
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OUTPUT

33       a      The array that stores the block upper-triangular matrix with ei‐
34              genvalues in the block diagonal elements after similarity trans‐
35              formation
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38       qriter The number of iterations of the QR algorithm
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41       qrerr  The  2-norm  of the first subdiagonal element A(2,1) after simi‐
42              larity transformation
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SEE ALSO

46       lis(3)
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48       http://www.ssisc.org/lis/
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53Man Page                          1 Nov 2014                  lis_array_qr(3f)