SUBROUTINE DLAREF( TYPE, A, LDA, WANTZ, Z, LDZ, BLOCK, IROW1, $ ICOL1, ISTART, ISTOP, ITMP1, ITMP2, LILOZ, $ LIHIZ, VECS, V2, V3, T1, T2, T3 ) * * -- ScaLAPACK auxiliary routine (version 1.5) -- * University of Tennessee, Knoxville, Oak Ridge National Laboratory, * and University of California, Berkeley. * May 1, 1997 * * .. Scalar Arguments .. LOGICAL BLOCK, WANTZ CHARACTER TYPE INTEGER ICOL1, IROW1, ISTART, ISTOP, ITMP1, ITMP2, LDA, $ LDZ, LIHIZ, LILOZ DOUBLE PRECISION T1, T2, T3, V2, V3 * .. * .. Array Arguments .. DOUBLE PRECISION A( LDA, * ), VECS( * ), Z( LDZ, * ) * .. * * Purpose * ======= * * DLAREF 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) 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. * * LILOZ * LIHIZ (local input) INTEGER * These serve the same purpose as ITMP1,ITMP2 but for Z * when WANTZ is set. * * 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. * * V2 * V3 * T1 * T2 * T3 (global input/output) DOUBLE PRECISION * 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, May 1, 1997 * * ===================================================================== * * .. Local Scalars .. INTEGER J, K DOUBLE PRECISION H11, H22, SUM, T12, T13, T22, T23, T32, T33, $ V22, V23, V32, V33, A1, A2, A3, A4, A5, B1, $ B2, B3, B4, B5, TMP1, TMP2, TMP3, SUM1, SUM2, $ SUM3, A11, A22 * .. * .. External Functions .. LOGICAL LSAME EXTERNAL LSAME * .. * .. Intrinsic Functions .. INTRINSIC MOD * .. * .. Executable Statements .. * IF( LSAME( TYPE, 'R' ) ) THEN IF( BLOCK ) THEN DO 30 K = ISTART, ISTOP - MOD( ISTOP-ISTART+1, 3 ), 3 V2 = VECS( ( K-1 )*3+1 ) V3 = VECS( ( K-1 )*3+2 ) T1 = VECS( ( K-1 )*3+3 ) V22 = VECS( ( K-1 )*3+4 ) V32 = VECS( ( K-1 )*3+5 ) T12 = VECS( ( K-1 )*3+6 ) V23 = VECS( ( K-1 )*3+7 ) V33 = VECS( ( K-1 )*3+8 ) T13 = VECS( ( K-1 )*3+9 ) T2 = T1*V2 T3 = T1*V3 T22 = T12*V22 T32 = T12*V32 T23 = T13*V23 T33 = T13*V33 DO 10 J = ITMP1, ITMP2-MOD(ITMP2-ITMP1+1,2), 2 A1 = A ( IROW1 , J ) A2 = A ( IROW1+1, J ) A3 = A ( IROW1+2, J ) A4 = A ( IROW1+3, J ) A5 = A ( IROW1+4, J ) B1 = A ( IROW1 , J+1 ) B2 = A ( IROW1+1, J+1 ) B3 = A ( IROW1+2, J+1 ) B4 = A ( IROW1+3, J+1 ) B5 = A ( IROW1+4, J+1 ) SUM1 = A1 + V2*A2 + V3*A3 A( IROW1 , J ) = A1 - SUM1 * T1 H11 = A2 - SUM1 * T2 H22 = A3 - SUM1 * T3 TMP1 = B1 + V2*B2 + V3*B3 A( IROW1 , J+1 ) = B1 - TMP1 * T1 A11 = B2 - TMP1 * T2 A22 = B3 - TMP1 * T3 SUM2 = H11 + V22*H22 + V32*A4 A( IROW1+1, J ) = H11 - SUM2 * T12 H11 = H22 - SUM2 * T22 H22 = A4 - SUM2 * T32 TMP2 = A11 + V22*A22 + V32*B4 A( IROW1+1, J+1 ) = A11 - TMP2 * T12 A11 = A22 - TMP2 * T22 A22 = B4 - TMP2 * T32 SUM3 = H11 + V23*H22 + V33*A5 A( IROW1+2, J ) = H11 - SUM3 * T13 A( IROW1+3, J ) = H22 - SUM3 * T23 A( IROW1+4, J ) = A5 - SUM3 * T33 TMP3 = A11 + V23*A22 + V33*B5 A( IROW1+2, J+1 ) = A11 - TMP3 * T13 A( IROW1+3, J+1 ) = A22 - TMP3 * T23 A( IROW1+4, J+1 ) = B5 - TMP3 * T33 10 CONTINUE DO 20 J = ITMP2-MOD(ITMP2-ITMP1+1,2)+1, ITMP2 SUM = A( IROW1, J ) + V2*A( IROW1+1, J ) + $ V3*A( IROW1+2, J ) A( IROW1, J ) = A( IROW1, J ) - SUM*T1 H11 = A( IROW1+1, J ) - SUM*T2 H22 = A( IROW1+2, J ) - SUM*T3 SUM = H11 + V22*H22 + V32*A( IROW1+3, J ) A( IROW1+1, J ) = H11 - SUM*T12 H11 = H22 - SUM*T22 H22 = A( IROW1+3, J ) - SUM*T32 SUM = H11 + V23*H22 + V33*A( IROW1+4, J ) A( IROW1+2, J ) = H11 - SUM*T13 A( IROW1+3, J ) = H22 - SUM*T23 A( IROW1+4, J ) = A( IROW1+4, J ) - SUM*T33 20 CONTINUE IROW1 = IROW1 + 3 30 CONTINUE DO 50 K = ISTOP - MOD( ISTOP-ISTART+1, 3 ) + 1, ISTOP V2 = VECS( ( K-1 )*3+1 ) V3 = VECS( ( K-1 )*3+2 ) T1 = VECS( ( K-1 )*3+3 ) T2 = T1*V2 T3 = T1*V3 DO 40 J = ITMP1, ITMP2 SUM = A( IROW1, J ) + V2*A( IROW1+1, J ) + $ V3*A( IROW1+2, J ) A( IROW1, J ) = A( IROW1, J ) - SUM*T1 A( IROW1+1, J ) = A( IROW1+1, J ) - SUM*T2 A( IROW1+2, J ) = A( IROW1+2, J ) - SUM*T3 40 CONTINUE IROW1 = IROW1 + 1 50 CONTINUE ELSE DO 60 J = ITMP1, ITMP2 SUM = A( IROW1, J ) + V2*A( IROW1+1, J ) + $ V3*A( IROW1+2, J ) A( IROW1, J ) = A( IROW1, J ) - SUM*T1 A( IROW1+1, J ) = A( IROW1+1, J ) - SUM*T2 A( IROW1+2, J ) = A( IROW1+2, J ) - SUM*T3 60 CONTINUE END IF ELSE * * Do column transforms * IF( BLOCK ) THEN DO 90 K = ISTART, ISTOP - MOD( ISTOP-ISTART+1, 3 ), 3 V2 = VECS( ( K-1 )*3+1 ) V3 = VECS( ( K-1 )*3+2 ) T1 = VECS( ( K-1 )*3+3 ) V22 = VECS( ( K-1 )*3+4 ) V32 = VECS( ( K-1 )*3+5 ) T12 = VECS( ( K-1 )*3+6 ) V23 = VECS( ( K-1 )*3+7 ) V33 = VECS( ( K-1 )*3+8 ) T13 = VECS( ( K-1 )*3+9 ) T2 = T1*V2 T3 = T1*V3 T22 = T12*V22 T32 = T12*V32 T23 = T13*V23 T33 = T13*V33 DO 70 J = ITMP1, ITMP2 SUM = A( J, ICOL1 ) + V2*A( J, ICOL1+1 ) + $ V3*A( J, ICOL1+2 ) A( J, ICOL1 ) = A( J, ICOL1 ) - SUM*T1 H11 = A( J, ICOL1+1 ) - SUM*T2 H22 = A( J, ICOL1+2 ) - SUM*T3 SUM = H11 + V22*H22 + V32*A( J, ICOL1+3 ) A( J, ICOL1+1 ) = H11 - SUM*T12 H11 = H22 - SUM*T22 H22 = A( J, ICOL1+3 ) - SUM*T32 SUM = H11 + V23*H22 + V33*A( J, ICOL1+4 ) A( J, ICOL1+2 ) = H11 - SUM*T13 A( J, ICOL1+3 ) = H22 - SUM*T23 A( J, ICOL1+4 ) = A( J, ICOL1+4 ) - SUM*T33 70 CONTINUE IF( WANTZ ) THEN DO 80 J = LILOZ, LIHIZ SUM = Z( J, ICOL1 ) + V2*Z( J, ICOL1+1 ) + $ V3*Z( J, ICOL1+2 ) Z( J, ICOL1 ) = Z( J, ICOL1 ) - SUM*T1 H11 = Z( J, ICOL1+1 ) - SUM*T2 H22 = Z( J, ICOL1+2 ) - SUM*T3 SUM = H11 + V22*H22 + V32*Z( J, ICOL1+3 ) Z( J, ICOL1+1 ) = H11 - SUM*T12 H11 = H22 - SUM*T22 H22 = Z( J, ICOL1+3 ) - SUM*T32 SUM = H11 + V23*H22 + V33*Z( J, ICOL1+4 ) Z( J, ICOL1+2 ) = H11 - SUM*T13 Z( J, ICOL1+3 ) = H22 - SUM*T23 Z( J, ICOL1+4 ) = Z( J, ICOL1+4 ) - SUM*T33 80 CONTINUE END IF ICOL1 = ICOL1 + 3 90 CONTINUE DO 120 K = ISTOP - MOD( ISTOP-ISTART+1, 3 ) + 1, ISTOP V2 = VECS( ( K-1 )*3+1 ) V3 = VECS( ( K-1 )*3+2 ) T1 = VECS( ( K-1 )*3+3 ) T2 = T1*V2 T3 = T1*V3 DO 100 J = ITMP1, ITMP2 SUM = A( J, ICOL1 ) + V2*A( J, ICOL1+1 ) + $ V3*A( J, ICOL1+2 ) A( J, ICOL1 ) = A( J, ICOL1 ) - SUM*T1 A( J, ICOL1+1 ) = A( J, ICOL1+1 ) - SUM*T2 A( J, ICOL1+2 ) = A( J, ICOL1+2 ) - SUM*T3 100 CONTINUE IF( WANTZ ) THEN DO 110 J = LILOZ, LIHIZ SUM = Z( J, ICOL1 ) + V2*Z( J, ICOL1+1 ) + $ V3*Z( J, ICOL1+2 ) Z( J, ICOL1 ) = Z( J, ICOL1 ) - SUM*T1 Z( J, ICOL1+1 ) = Z( J, ICOL1+1 ) - SUM*T2 Z( J, ICOL1+2 ) = Z( J, ICOL1+2 ) - SUM*T3 110 CONTINUE END IF ICOL1 = ICOL1 + 1 120 CONTINUE ELSE DO 130 J = ITMP1, ITMP2 SUM = A( J, ICOL1 ) + V2*A( J, ICOL1+1 ) + $ V3*A( J, ICOL1+2 ) A( J, ICOL1 ) = A( J, ICOL1 ) - SUM*T1 A( J, ICOL1+1 ) = A( J, ICOL1+1 ) - SUM*T2 A( J, ICOL1+2 ) = A( J, ICOL1+2 ) - SUM*T3 130 CONTINUE END IF END IF RETURN * * End of DLAREF * END