dlaed5.f man page
dlaed5.f subroutine dlaed5 (I, D, Z, DELTA, RHO, DLAM) DLAED5 used by sstedc. Solves the 2-by-2 secular equation. Purpose: I D Z DELTA RHO DLAM Univ. of Tennessee Univ. of California Berkeley Univ. of Colorado Denver NAG Ltd. December 2016 Ren-Cang Li, Computer Science Division, University of California at Berkeley, USA Definition at line 110 of file dlaed5.f. Generated automatically by Doxygen for LAPACK from the source code. The man page dlaed5(3) is an alias of dlaed5.f(3).Synopsis
Functions/Subroutines
DLAED5 used by sstedc. Solves the 2-by-2 secular equation. Function/Subroutine Documentation
subroutine dlaed5 (integer I, double precision, dimension( 2 ) D, double precision, dimension( 2 ) Z, double precision, dimension( 2 ) DELTA, double precision RHO, double precision DLAM)
This subroutine computes the I-th eigenvalue of a symmetric rank-one
modification of a 2-by-2 diagonal matrix
diag( D ) + RHO * Z * transpose(Z) .
The diagonal elements in the array D are assumed to satisfy
D(i) < D(j) for i < j .
We also assume RHO > 0 and that the Euclidean norm of the vector
Z is one.
I is INTEGER
The index of the eigenvalue to be computed. I = 1 or I = 2.
D is DOUBLE PRECISION array, dimension (2)
The original eigenvalues. We assume D(1) < D(2).
Z is DOUBLE PRECISION array, dimension (2)
The components of the updating vector.
DELTA is DOUBLE PRECISION array, dimension (2)
The vector DELTA contains the information necessary
to construct the eigenvectors.
RHO is DOUBLE PRECISION
The scalar in the symmetric updating formula.
DLAM is DOUBLE PRECISION
The computed lambda_I, the I-th updated eigenvalue.
Author
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