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.TH DLASQ3 l "15 June 2000" "LAPACK version 3.0" ")"
.SH NAME
DLASQ3 - check for deflation, computes a shift (TAU) and calls dqds
.SH SYNOPSIS
.TP 19
SUBROUTINE DLASQ3(
I0, N0, Z, PP, DMIN, SIGMA, DESIG, QMAX, NFAIL,
ITER, NDIV, IEEE )
.TP 19
.ti +4
LOGICAL
IEEE
.TP 19
.ti +4
INTEGER
I0, ITER, N0, NDIV, NFAIL, PP
.TP 19
.ti +4
DOUBLE
PRECISION DESIG, DMIN, QMAX, SIGMA
.TP 19
.ti +4
DOUBLE
PRECISION Z( * )
.SH PURPOSE
DLASQ3 checks for deflation, computes a shift (TAU) and calls dqds. In case of failure it changes shifts, and tries again until output
is positive.
.br
.SH ARGUMENTS
.TP 7
I0 (input) INTEGER
First index.
.TP 7
N0 (input) INTEGER
Last index.
.TP 7
Z (input) DOUBLE PRECISION array, dimension ( 4*N )
Z holds the qd array.
.TP 7
PP (input) INTEGER
PP=0 for ping, PP=1 for pong.
.TP 7
DMIN (output) DOUBLE PRECISION
Minimum value of d.
.TP 7
SIGMA (output) DOUBLE PRECISION
Sum of shifts used in current segment.
.TP 7
DESIG (input/output) DOUBLE PRECISION
Lower order part of SIGMA
.TP 7
QMAX (input) DOUBLE PRECISION
Maximum value of q.
.TP 7
NFAIL (output) INTEGER
Number of times shift was too big.
.TP 7
ITER (output) INTEGER
Number of iterations.
.TP 7
NDIV (output) INTEGER
Number of divisions.
.TP 7
TTYPE (output) INTEGER
Shift type.
.TP 7
IEEE (input) LOGICAL
Flag for IEEE or non IEEE arithmetic (passed to DLASQ5).
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