DLAREF(l) | LAPACK auxiliary routine (version 1.5) | DLAREF(l) |
NAME¶
DLAREF - applie one or several Householder reflectors of size 3 to one or two matrices (if column is specified) on either their rows or columnsSYNOPSIS¶
- SUBROUTINE DLAREF(
- 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
- DOUBLE
- PRECISION T1, T2, T3, V2, V3
- DOUBLE
- PRECISION A( LDA, * ), VECS( * ), Z( LDZ, * )
PURPOSE¶
DLAREF applies one or several Householder reflectors of size 3to 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) DOUBLE PRECISION 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) DOUBLE PRECISION 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.
- VECS (global input) DOUBLE PRECISION 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.
12 May 1997 | LAPACK version 1.5 |