dlasq6.f man page

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.

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

          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 Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date:

September 2012

Definition at line 119 of file dlasq6.f.