DragonFly On-Line Manual Pages

SLAREF(l)                              )                             SLAREF(l)

NAME
       SLAREF - applie one or several Householder reflectors of size 3 to one
       or two matrices (if column is specified) on either their rows or
       columns

SYNOPSIS
       SUBROUTINE SLAREF( TYPE, A, LDA, WANTZ, Z, LDZ, BLOCK, IROW1, ICOL1,
                          ISTART, ISTOP, ITMP1, ITMP2, LILOZ, LIHIZ, VECS, V2,
                          V3, T1, T2, T3 )
           LOGICAL BLOCK, WANTZ
           CHARACTER TYPE
           INTEGER ICOL1, IROW1, ISTART, ISTOP, ITMP1, ITMP2, LDA, LDZ, LIHIZ,
       LILOZ
           REAL T1, T2, T3, V2, V3
           REAL A( LDA, * ), VECS( * ), Z( LDZ, * )

PURPOSE
       SLAREF applies one or several Householder reflectors of size 3 to one
       or two matrices (if column is specified) on either their rows or
       columns.

ARGUMENTS
       TYPE    (global input) CHARACTER*1
               If 'R': Apply reflectors to the rows of the matrix (apply from
               left) Otherwise: Apply reflectors to the columns of the matrix
               Unchanged on exit.

       A       (global input/output) REAL array, (LDA,*)
               On entry, the matrix to receive the reflections.  The updated
               matrix on exit.

       LDA     (local input) INTEGER
               On entry, the leading dimension of A.  Unchanged on exit.

       WANTZ   (global input) LOGICAL
               If .TRUE., then apply any column reflections to Z as well.  If
               .FALSE., then do no additional work on Z.

       Z       (global input/output) REAL array, (LDZ,*)
               On entry, the second matrix to receive column reflections.
               This is changed only if WANTZ is set.

       LDZ     (local input) INTEGER
               On entry, the leading dimension of Z.  Unchanged on exit.

       BLOCK   (global input) LOGICAL
               If .TRUE., then apply several reflectors at once and read their
               data from the VECS array.  If .FALSE., apply the single
               reflector given by V2, V3, T1, T2, and T3.

       IROW1   (local input/output) INTEGER
               On entry, the local row element of A.  Undefined on output.

       ICOL1   (local input/output) INTEGER
               On entry, the local column element of A.  Undefined on output.

       ISTART  (global input) INTEGER
               Specifies the "number" of the first reflector.  This is used as
               an index into VECS if BLOCK is set.  ISTART is ignored if BLOCK
               is .FALSE..

       ISTOP   (global input) INTEGER
               Specifies the "number" of the last reflector.  This is used as
               an index into VECS if BLOCK is set.  ISTOP is ignored if BLOCK
               is .FALSE..

       ITMP1   (local input) INTEGER
               Starting range into A.  For rows, this is the local first
               column.  For columns, this is the local first row.

       ITMP2   (local input) INTEGER
               Ending range into A.  For rows, this is the local last column.
               For columns, this is the local last row.

               LILOZ LIHIZ   (local input) INTEGER These serve the same
               purpose as ITMP1,ITMP2 but for Z when WANTZ is set.

       VECS    (global input) REAL array of size 3*N (matrix
               size) This holds the size 3 reflectors one after another and
               this is only accessed when BLOCK is .TRUE.

               V2 V3 T1 T2 T3      (global input/output) REAL This holds
               information on a single size 3 Householder reflector and is
               read when BLOCK is .FALSE., and overwritten when BLOCK is
               .TRUE.

               Implemented by:  G. Henry, November 17, 1996

ScaLAPACK version 1.7           13 August 2001                       SLAREF(l)