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.
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 is INTEGER
First index.
N0
N0 is INTEGER
Last index.
Z
Z is REAL array, dimension ( 4*N0 )
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
Increment NFAIL by 1 each time the shift was too big.
ITER
ITER is INTEGER
Increment ITER by 1 for each iteration.
NDIV
NDIV is INTEGER
Increment NDIV by 1 for each division.
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 California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date:
Definition at line 184 of file slasq3.f.
Generated automatically by Doxygen for LAPACK from the source code.