SRC/dlaqz1.f(3) | Library Functions Manual | SRC/dlaqz1.f(3) |
NAME
SRC/dlaqz1.f
SYNOPSIS
Functions/Subroutines
subroutine dlaqz1 (a, lda, b, ldb, sr1, sr2, si, beta1,
beta2, v)
DLAQZ1
Function/Subroutine Documentation
subroutine dlaqz1 (double precision, dimension( lda, * ), intent(in) a, integer, intent(in) lda, double precision, dimension( ldb, * ), intent(in) b, integer, intent(in) ldb, double precision, intent(in) sr1, double precision, intent(in) sr2, double precision, intent(in) si, double precision, intent(in) beta1, double precision, intent(in) beta2, double precision, dimension( * ), intent(out) v)
DLAQZ1
Purpose:
Given a 3-by-3 matrix pencil (A,B), DLAQZ1 sets v to a scalar multiple of the first column of the product (*) K = (A - (beta2*sr2 - i*si)*B)*B^(-1)*(beta1*A - (sr2 + i*si2)*B)*B^(-1). It is assumed that either 1) sr1 = sr2 or 2) si = 0. This is useful for starting double implicit shift bulges in the QZ algorithm.
Parameters
A
A is DOUBLE PRECISION array, dimension (LDA,N) The 3-by-3 matrix A in (*).
LDA
LDA is INTEGER The leading dimension of A as declared in the calling procedure.
B
B is DOUBLE PRECISION array, dimension (LDB,N) The 3-by-3 matrix B in (*).
LDB
LDB is INTEGER The leading dimension of B as declared in the calling procedure.
SR1
SR1 is DOUBLE PRECISION
SR2
SR2 is DOUBLE PRECISION
SI
SI is DOUBLE PRECISION
BETA1
BETA1 is DOUBLE PRECISION
BETA2
BETA2 is DOUBLE PRECISION
V
V is DOUBLE PRECISION array, dimension (N) A scalar multiple of the first column of the matrix K in (*).
Author
Thijs Steel, KU Leuven
Date
May 2020
Definition at line 125 of file dlaqz1.f.
Author
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