dlasq6(3S)

NAME
     DLASQ6 - compute 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( * )

IMPLEMENTATION
     These routines are part of the SCSL Scientific Library and can be loaded
     using either the -lscs or the -lscs_mp option.  The -lscs_mp option
     directs the linker to use the multi-processor version of the library.

     When linking to SCSL with -lscs or -lscs_mp, the default integer size is
     4 bytes (32 bits). Another version of SCSL is available in which integers
     are 8 bytes (64 bits).  This version allows the user access to larger
     memory sizes and helps when porting legacy Cray codes.  It can be loaded
     by using the -lscs_i8 option or the -lscs_i8_mp option. A program may use
     only one of the two versions; 4-byte integer and 8-byte integer library
     calls cannot be mixed.

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).

SEE ALSO
     INTRO_LAPACK(3S), INTRO_SCSL(3S)

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