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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