1SLAED5(1)                LAPACK routine (version 3.2)                SLAED5(1)
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NAME

6       SLAED5 - subroutine compute the I-th eigenvalue of a symmetric rank-one
7       modification of a 2-by-2 diagonal matrix   diag( D ) + RHO  The  diago‐
8       nal  elements in the array D are assumed to satisfy   D(i) < D(j) for i
9       < j
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SYNOPSIS

12       SUBROUTINE SLAED5( I, D, Z, DELTA, RHO, DLAM )
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14           INTEGER        I
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16           REAL           DLAM, RHO
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18           REAL           D( 2 ), DELTA( 2 ), Z( 2 )
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PURPOSE

21       This subroutine computes the I-th eigenvalue of  a  symmetric  rank-one
22       modification  of  a  2-by-2  diagonal matrix We also assume RHO > 0 and
23       that the Euclidean norm of the vector Z is one.
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ARGUMENTS

26       I      (input) INTEGER
27              The index of the eigenvalue to be computed.  I = 1 or I = 2.
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29       D      (input) REAL array, dimension (2)
30              The original eigenvalues.  We assume D(1) < D(2).
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32       Z      (input) REAL array, dimension (2)
33              The components of the updating vector.
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35       DELTA  (output) REAL array, dimension (2)
36              The vector DELTA contains the information necessary to construct
37              the eigenvectors.
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39       RHO    (input) REAL
40              The scalar in the symmetric updating formula.
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42       DLAM   (output) REAL
43              The computed lambda_I, the I-th updated eigenvalue.
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FURTHER DETAILS

46       Based on contributions by
47          Ren-Cang Li, Computer Science Division, University of California
48          at Berkeley, USA
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52 LAPACK routine (version 3.2)    November 2008                       SLAED5(1)