slasq3.f man page

slasq3.f —

Synopsis

Functions/Subroutines

subroutine slasq3 (I0, N0, Z, PP, DMIN, SIGMA, DESIG, QMAX, NFAIL, ITER, NDIV, IEEE, TTYPE, DMIN1, DMIN2, DN, DN1, DN2, G, TAU)
SLASQ3 checks for deflation, computes a shift and calls dqds. Used by sbdsqr.

Function/Subroutine Documentation

subroutine slasq3 (integerI0, integerN0, real, dimension( * )Z, integerPP, realDMIN, realSIGMA, realDESIG, realQMAX, integerNFAIL, integerITER, integerNDIV, logicalIEEE, integerTTYPE, realDMIN1, realDMIN2, realDN, realDN1, realDN2, realG, realTAU)

SLASQ3 checks for deflation, computes a shift and calls dqds. Used by sbdsqr.

Purpose:

SLASQ3 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 REAL 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 REAL
Minimum value of d.

SIGMA

 SIGMA is REAL
Sum of shifts used in current segment.

DESIG

 DESIG is REAL
Lower order part of SIGMA

QMAX

 QMAX is REAL
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 SLASQ5).

TTYPE

 TTYPE is INTEGER
Shift type.

DMIN1

DMIN1 is REAL

DMIN2

DMIN2 is REAL

DN

DN is REAL

DN1

DN1 is REAL

DN2

DN2 is REAL

G

G is REAL

TAU

 TAU is REAL

These are passed as arguments in order to save their values
between calls to SLASQ3.

Author:

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date:

September 2012

Definition at line 181 of file slasq3.f.

Author

Generated automatically by Doxygen for LAPACK from the source code.

Referenced By

slasq3(3) is an alias of slasq3.f(3).

Sat Nov 16 2013 Version 3.4.2 LAPACK