dlasq3.f man page

dlasq3.f —

Synopsis

Functions/Subroutines

subroutine dlasq3 (I0, N0, Z, PP, DMIN, SIGMA, DESIG, QMAX, NFAIL, ITER, NDIV, IEEE, TTYPE, DMIN1, DMIN2, DN, DN1, DN2, G, TAU)
DLASQ3 checks for deflation, computes a shift and calls dqds. Used by sbdsqr.

Function/Subroutine Documentation

subroutine dlasq3 (integerI0, integerN0, double precision, dimension( * )Z, integerPP, double precisionDMIN, double precisionSIGMA, double precisionDESIG, double precisionQMAX, integerNFAIL, integerITER, integerNDIV, logicalIEEE, integerTTYPE, double precisionDMIN1, double precisionDMIN2, double precisionDN, double precisionDN1, double precisionDN2, double precisionG, double precisionTAU)

DLASQ3 checks for deflation, computes a shift and calls dqds. Used by sbdsqr.

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.

Parameters:

I0

 I0 is INTEGER
First index.

N0

 N0 is INTEGER
Last index.

Z

 Z is DOUBLE PRECISION array, dimension ( 4*N )
Z holds the qd array.

PP

 PP is INTEGER
PP=0 for ping, PP=1 for pong.
PP=2 indicates that flipping was applied to the Z array   
and that the initial tests for deflation should not be 
performed.

DMIN

 DMIN is DOUBLE PRECISION
Minimum value of d.

SIGMA

 SIGMA is DOUBLE PRECISION
Sum of shifts used in current segment.

DESIG

 DESIG is DOUBLE PRECISION
Lower order part of SIGMA

QMAX

 QMAX is DOUBLE PRECISION
Maximum value of q.

NFAIL

 NFAIL is INTEGER
Number of times shift was too big.

ITER

 ITER is INTEGER
Number of iterations.

NDIV

 NDIV is INTEGER
Number of divisions.

IEEE

 IEEE is LOGICAL
Flag for IEEE or non IEEE arithmetic (passed to DLASQ5).

TTYPE

 TTYPE is INTEGER
Shift type.

DMIN1

DMIN1 is DOUBLE PRECISION

DMIN2

DMIN2 is DOUBLE PRECISION

DN

DN is DOUBLE PRECISION

DN1

DN1 is DOUBLE PRECISION

DN2

DN2 is DOUBLE PRECISION

G

G is DOUBLE PRECISION

TAU

 TAU is DOUBLE PRECISION

These are passed as arguments in order to save their values
between calls to DLASQ3.

Author:

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date:

September 2012

Definition at line 181 of file dlasq3.f.

Author

Generated automatically by Doxygen for LAPACK from the source code.

Referenced By

dlasq3(3) is an alias of dlasq3.f(3).

Sat Nov 16 2013 Version 3.4.2 LAPACK