dlasq3.f (3) Linux Manual 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

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