SRC/slasq4.f(3) | Library Functions Manual | SRC/slasq4.f(3) |
NAME
SRC/slasq4.f
SYNOPSIS
Functions/Subroutines
subroutine slasq4 (i0, n0, z, pp, n0in, dmin, dmin1, dmin2,
dn, dn1, dn2, tau, ttype, g)
SLASQ4 computes an approximation to the smallest eigenvalue using
values of d from the previous transform. Used by sbdsqr.
Function/Subroutine Documentation
subroutine slasq4 (integer i0, integer n0, real, dimension( * ) z, integer pp, integer n0in, real dmin, real dmin1, real dmin2, real dn, real dn1, real dn2, real tau, integer ttype, real g)
SLASQ4 computes an approximation to the smallest eigenvalue using values of d from the previous transform. Used by sbdsqr.
Purpose:
SLASQ4 computes an approximation TAU to the smallest eigenvalue using values of d from the previous transform.
Parameters
I0
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.
N0IN
N0IN is INTEGER The value of N0 at start of EIGTEST.
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(N)
DN1
DN1 is REAL d(N-1)
DN2
DN2 is REAL d(N-2)
TAU
TAU is REAL This is the shift.
TTYPE
TTYPE is INTEGER Shift type.
G
G is REAL G is passed as an argument in order to save its value between calls to SLASQ4.
Author
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Further Details:
CNST1 = 9/16
Definition at line 149 of file slasq4.f.
Author
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