NAME¶

DLASQ6 - computes one dqd (shift equal to zero) transform in ping-pong form, with protection against underflow and overflow

SYNOPSIS¶

SUBROUTINE DLASQ6(

I0, N0, Z, PP, DMIN, DMIN1, DMIN2, DN, DNM1, DNM2 )

INTEGER I0, N0, PP DOUBLE PRECISION DMIN, DMIN1, DMIN2, DN, DNM1, DNM2 DOUBLE PRECISION Z( * )

PURPOSE¶

DLASQ6 computes one dqd (shift equal to zero) transform in ping-pong form, with protection against underflow and overflow.

ARGUMENTS¶

I0 (input) INTEGER

First index.

N0 (input) INTEGER

Last index.

Z (input) DOUBLE PRECISION array, dimension ( 4*N )

Z holds the qd array. EMIN is stored in Z(4*N0) to avoid an extra argument.

PP (input) INTEGER

PP=0 for ping, PP=1 for pong.

DMIN (output) DOUBLE PRECISION

Minimum value of d. DMIN1 (output) DOUBLE PRECISION Minimum value of d, excluding D( N0 ). DMIN2 (output) DOUBLE PRECISION Minimum value of d, excluding D( N0 ) and D( N0-1 ).

DN (output) DOUBLE PRECISION

d(N0), the last value of d.

DNM1 (output) DOUBLE PRECISION

d(N0-1).

DNM2 (output) DOUBLE PRECISION

d(N0-2).