| lasq6(3) | LAPACK | lasq6(3) |
lasq6 - lasq6: dqds step
subroutine dlasq6 (i0, n0, z, pp, dmin, dmin1, dmin2, dn,
dnm1, dnm2)
DLASQ6 computes one dqd transform in ping-pong form. Used by sbdsqr and
sstegr. subroutine slasq6 (i0, n0, z, pp, dmin, dmin1, dmin2, dn,
dnm1, dnm2)
SLASQ6 computes one dqd transform in ping-pong form. Used by sbdsqr and
sstegr.
DLASQ6 computes one dqd transform in ping-pong form. Used by sbdsqr and sstegr.
Purpose:
DLASQ6 computes one dqd (shift equal to zero) transform in
ping-pong form, with protection against underflow and overflow.
Parameters
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. EMIN is stored in Z(4*N0) to avoid
an extra argument.
PP
PP is INTEGER
PP=0 for ping, PP=1 for pong.
DMIN
DMIN is DOUBLE PRECISION
Minimum value of d.
DMIN1
DMIN1 is DOUBLE PRECISION
Minimum value of d, excluding D( N0 ).
DMIN2
DMIN2 is DOUBLE PRECISION
Minimum value of d, excluding D( N0 ) and D( N0-1 ).
DN
DN is DOUBLE PRECISION
d(N0), the last value of d.
DNM1
DNM1 is DOUBLE PRECISION
d(N0-1).
DNM2
DNM2 is DOUBLE PRECISION
d(N0-2).
Author
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
SLASQ6 computes one dqd transform in ping-pong form. Used by sbdsqr and sstegr.
Purpose:
SLASQ6 computes one dqd (shift equal to zero) transform in
ping-pong form, with protection against underflow and overflow.
Parameters
I0 is INTEGER
First index.
N0
N0 is INTEGER
Last index.
Z
Z is REAL array, dimension ( 4*N )
Z holds the qd array. EMIN is stored in Z(4*N0) to avoid
an extra argument.
PP
PP is INTEGER
PP=0 for ping, PP=1 for pong.
DMIN
DMIN is REAL
Minimum value of d.
DMIN1
DMIN1 is REAL
Minimum value of d, excluding D( N0 ).
DMIN2
DMIN2 is REAL
Minimum value of d, excluding D( N0 ) and D( N0-1 ).
DN
DN is REAL
d(N0), the last value of d.
DNM1
DNM1 is REAL
d(N0-1).
DNM2
DNM2 is REAL
d(N0-2).
Author
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
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| Thu Aug 7 2025 17:26:25 | Version 3.12.0 |