dlasq4.f(3)

NAME
dlasq4.f -

SYNOPSIS

  Functions/Subroutines

subroutine dlasq4 (I0, N0, Z, PP, N0IN, DMIN, DMIN1, DMIN2, DN, DN1, DN2, TAU, TTYPE, G)
DLASQ4 computes an approximation to the smallest eigenvalue using values of d from the previous transform. Used by sbdsqr.

Function/Subroutine Documentation

  subroutine dlasq4 (integerI0, integerN0, double precision, dimension( * )Z, integerPP, integerN0IN, double precisionDMIN, double precisionDMIN1, double precisionDMIN2, double precisionDN, double precisionDN1, double precisionDN2, double precisionTAU, integerTTYPE, double precisionG)

DLASQ4 computes an approximation to the smallest eigenvalue using values of d from the previous transform. Used by sbdsqr.

Purpose:

     DLASQ4 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 DOUBLE PRECISION array, dimension ( 4*N )
            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 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(N)

    DN1

              DN1 is DOUBLE PRECISION
            d(N-1)

    DN2

              DN2 is DOUBLE PRECISION
            d(N-2)

    TAU

              TAU is DOUBLE PRECISION
            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 DLASQ4.

Author:
    Univ. of Tennessee

    Univ. of California Berkeley

    Univ. of Colorado Denver

    NAG Ltd.

Date:
    September 2012

Further Details:

      CNST1 = 9/16

Definition at line 151 of file dlasq4.f.

Author

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