diff options
Diffstat (limited to '2.3-1/src/fortran/lapack/dlatzm.f')
| -rw-r--r-- | 2.3-1/src/fortran/lapack/dlatzm.f | 142 |
1 files changed, 142 insertions, 0 deletions
diff --git a/2.3-1/src/fortran/lapack/dlatzm.f b/2.3-1/src/fortran/lapack/dlatzm.f new file mode 100644 index 00000000..2467ab60 --- /dev/null +++ b/2.3-1/src/fortran/lapack/dlatzm.f @@ -0,0 +1,142 @@ + SUBROUTINE DLATZM( SIDE, M, N, V, INCV, TAU, C1, C2, LDC, WORK ) +* +* -- LAPACK routine (version 3.1) -- +* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. +* November 2006 +* +* .. Scalar Arguments .. + CHARACTER SIDE + INTEGER INCV, LDC, M, N + DOUBLE PRECISION TAU +* .. +* .. Array Arguments .. + DOUBLE PRECISION C1( LDC, * ), C2( LDC, * ), V( * ), WORK( * ) +* .. +* +* Purpose +* ======= +* +* This routine is deprecated and has been replaced by routine DORMRZ. +* +* DLATZM applies a Householder matrix generated by DTZRQF to a matrix. +* +* Let P = I - tau*u*u', u = ( 1 ), +* ( v ) +* where v is an (m-1) vector if SIDE = 'L', or a (n-1) vector if +* SIDE = 'R'. +* +* If SIDE equals 'L', let +* C = [ C1 ] 1 +* [ C2 ] m-1 +* n +* Then C is overwritten by P*C. +* +* If SIDE equals 'R', let +* C = [ C1, C2 ] m +* 1 n-1 +* Then C is overwritten by C*P. +* +* Arguments +* ========= +* +* SIDE (input) CHARACTER*1 +* = 'L': form P * C +* = 'R': form C * P +* +* M (input) INTEGER +* The number of rows of the matrix C. +* +* N (input) INTEGER +* The number of columns of the matrix C. +* +* V (input) DOUBLE PRECISION array, dimension +* (1 + (M-1)*abs(INCV)) if SIDE = 'L' +* (1 + (N-1)*abs(INCV)) if SIDE = 'R' +* The vector v in the representation of P. V is not used +* if TAU = 0. +* +* INCV (input) INTEGER +* The increment between elements of v. INCV <> 0 +* +* TAU (input) DOUBLE PRECISION +* The value tau in the representation of P. +* +* C1 (input/output) DOUBLE PRECISION array, dimension +* (LDC,N) if SIDE = 'L' +* (M,1) if SIDE = 'R' +* On entry, the n-vector C1 if SIDE = 'L', or the m-vector C1 +* if SIDE = 'R'. +* +* On exit, the first row of P*C if SIDE = 'L', or the first +* column of C*P if SIDE = 'R'. +* +* C2 (input/output) DOUBLE PRECISION array, dimension +* (LDC, N) if SIDE = 'L' +* (LDC, N-1) if SIDE = 'R' +* On entry, the (m - 1) x n matrix C2 if SIDE = 'L', or the +* m x (n - 1) matrix C2 if SIDE = 'R'. +* +* On exit, rows 2:m of P*C if SIDE = 'L', or columns 2:m of C*P +* if SIDE = 'R'. +* +* LDC (input) INTEGER +* The leading dimension of the arrays C1 and C2. LDC >= (1,M). +* +* WORK (workspace) DOUBLE PRECISION array, dimension +* (N) if SIDE = 'L' +* (M) if SIDE = 'R' +* +* ===================================================================== +* +* .. Parameters .. + DOUBLE PRECISION ONE, ZERO + PARAMETER ( ONE = 1.0D+0, ZERO = 0.0D+0 ) +* .. +* .. External Subroutines .. + EXTERNAL DAXPY, DCOPY, DGEMV, DGER +* .. +* .. External Functions .. + LOGICAL LSAME + EXTERNAL LSAME +* .. +* .. Intrinsic Functions .. + INTRINSIC MIN +* .. +* .. Executable Statements .. +* + IF( ( MIN( M, N ).EQ.0 ) .OR. ( TAU.EQ.ZERO ) ) + $ RETURN +* + IF( LSAME( SIDE, 'L' ) ) THEN +* +* w := C1 + v' * C2 +* + CALL DCOPY( N, C1, LDC, WORK, 1 ) + CALL DGEMV( 'Transpose', M-1, N, ONE, C2, LDC, V, INCV, ONE, + $ WORK, 1 ) +* +* [ C1 ] := [ C1 ] - tau* [ 1 ] * w' +* [ C2 ] [ C2 ] [ v ] +* + CALL DAXPY( N, -TAU, WORK, 1, C1, LDC ) + CALL DGER( M-1, N, -TAU, V, INCV, WORK, 1, C2, LDC ) +* + ELSE IF( LSAME( SIDE, 'R' ) ) THEN +* +* w := C1 + C2 * v +* + CALL DCOPY( M, C1, 1, WORK, 1 ) + CALL DGEMV( 'No transpose', M, N-1, ONE, C2, LDC, V, INCV, ONE, + $ WORK, 1 ) +* +* [ C1, C2 ] := [ C1, C2 ] - tau* w * [ 1 , v'] +* + CALL DAXPY( M, -TAU, WORK, 1, C1, 1 ) + CALL DGER( M, N-1, -TAU, WORK, 1, V, INCV, C2, LDC ) + END IF +* + RETURN +* +* End of DLATZM +* + END |