LAPACK
3.4.2
LAPACK: Linear Algebra PACKage

Go to the source code of this file.
Functions/Subroutines  
subroutine  slaed5 (I, D, Z, DELTA, RHO, DLAM) 
SLAED5 used by sstedc. Solves the 2by2 secular equation. 
subroutine slaed5  (  integer  I, 
real, dimension( 2 )  D,  
real, dimension( 2 )  Z,  
real, dimension( 2 )  DELTA,  
real  RHO,  
real  DLAM  
) 
SLAED5 used by sstedc. Solves the 2by2 secular equation.
Download SLAED5 + dependencies [TGZ] [ZIP] [TXT]This subroutine computes the Ith eigenvalue of a symmetric rankone modification of a 2by2 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.
[in]  I  I is INTEGER The index of the eigenvalue to be computed. I = 1 or I = 2. 
[in]  D  D is REAL array, dimension (2) The original eigenvalues. We assume D(1) < D(2). 
[in]  Z  Z is REAL array, dimension (2) The components of the updating vector. 
[out]  DELTA  DELTA is REAL array, dimension (2) The vector DELTA contains the information necessary to construct the eigenvectors. 
[in]  RHO  RHO is REAL The scalar in the symmetric updating formula. 
[out]  DLAM  DLAM is REAL The computed lambda_I, the Ith updated eigenvalue. 
Definition at line 109 of file slaed5.f.