SLAED9 (3) Linux Manual Page

slaed9.f –

Synopsis

Functions/Subroutines

subroutine slaed9 (K, KSTART, KSTOP, N, D, Q, LDQ, RHO, DLAMDA, W, S, LDS, INFO)
SLAED9 used by sstedc. Finds the roots of the secular equation and updates the eigenvectors. Used when the original matrix is dense.

Function/Subroutine Documentation

subroutine slaed9 (integerK, integerKSTART, integerKSTOP, integerN, real, dimension( * )D, real, dimension( ldq, * )Q, integerLDQ, realRHO, real, dimension( * )DLAMDA, real, dimension( * )W, real, dimension( lds, * )S, integerLDS, integerINFO)

SLAED9 used by sstedc. Finds the roots of the secular equation and updates the eigenvectors. Used when the original matrix is dense.

Purpose:

 SLAED9 finds the roots of the secular equation, as defined by the

 values in D, Z, and RHO, between KSTART and KSTOP. It makes the

 appropriate calls to SLAED4 and then stores the new matrix of

 eigenvectors for use in calculating the next level of Z vectors.

 

Parameters:

K

 K is INTEGER

 The number of terms in the rational function to be solved by

 SLAED4. K >= 0.

KSTART

 KSTART is INTEGER

KSTOP

 KSTOP is INTEGER

 The updated eigenvalues Lambda(I), KSTART <= I <= KSTOP

 are to be computed. 1 <= KSTART <= KSTOP <= K.

N

 N is INTEGER

 The number of rows and columns in the Q matrix.

 N >= K (delation may result in N > K).

D

 D is REAL array, dimension (N)

 D(I) contains the updated eigenvalues

 for KSTART <= I <= KSTOP.

Q

 Q is REAL array, dimension (LDQ,N)

LDQ

 LDQ is INTEGER

 The leading dimension of the array Q. LDQ >= max( 1, N ).

RHO

 RHO is REAL

 The value of the parameter in the rank one update equation.

 RHO >= 0 required.

DLAMDA

 DLAMDA is REAL array, dimension (K)

 The first K elements of this array contain the old roots

 of the deflated updating problem. These are the poles

 of the secular equation.

W

 W is REAL array, dimension (K)

 The first K elements of this array contain the components

 of the deflation-adjusted updating vector.

S

 S is REAL array, dimension (LDS, K)

 Will contain the eigenvectors of the repaired matrix which

 will be stored for subsequent Z vector calculation and

 multiplied by the previously accumulated eigenvectors

 to update the system.

LDS

 LDS is INTEGER

 The leading dimension of S. LDS >= max( 1, K ).

INFO

 INFO is INTEGER

 = 0: successful exit.

 < 0: if INFO = -i, the i-th argument had an illegal value.

 > 0: if INFO = 1, an eigenvalue did not converge

 

Author:

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date:

September 2012

Contributors:

Jeff Rutter, Computer Science Division, University of California at Berkeley, USA

Definition at line 156 of file slaed9.f.

Author

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