dlasq3 (3)  Linux Manuals
NAME
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.
N0N0 is INTEGER Last index.
ZZ is DOUBLE PRECISION array, dimension ( 4*N ) Z holds the qd array.
PPPP 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.
DMINDMIN is DOUBLE PRECISION Minimum value of d.
SIGMASIGMA is DOUBLE PRECISION Sum of shifts used in current segment.
DESIGDESIG is DOUBLE PRECISION Lower order part of SIGMA
QMAXQMAX is DOUBLE PRECISION Maximum value of q.
NFAILNFAIL is INTEGER Number of times shift was too big.
ITERITER is INTEGER Number of iterations.
NDIVNDIV is INTEGER Number of divisions.
IEEEIEEE is LOGICAL Flag for IEEE or non IEEE arithmetic (passed to DLASQ5).
TTYPETTYPE is INTEGER Shift type.
DMIN1DMIN1 is DOUBLE PRECISION
DMIN2DMIN2 is DOUBLE PRECISION
DNDN is DOUBLE PRECISION
DN1DN1 is DOUBLE PRECISION
DN2DN2 is DOUBLE PRECISION
GG is DOUBLE PRECISION
TAUTAU 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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