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author | jason <jason@8a072113-8704-0410-8d35-dd094bca7971> | 2008-10-28 01:38:50 +0000 |
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committer | jason <jason@8a072113-8704-0410-8d35-dd094bca7971> | 2008-10-28 01:38:50 +0000 |
commit | baba851215b44ac3b60b9248eb02bcce7eb76247 (patch) | |
tree | 8c0f5c006875532a30d4409f5e94b0f310ff00a7 /SRC/dlasr.f | |
download | lapack-baba851215b44ac3b60b9248eb02bcce7eb76247.tar.gz lapack-baba851215b44ac3b60b9248eb02bcce7eb76247.tar.bz2 lapack-baba851215b44ac3b60b9248eb02bcce7eb76247.zip |
Move LAPACK trunk into position.
Diffstat (limited to 'SRC/dlasr.f')
-rw-r--r-- | SRC/dlasr.f | 361 |
1 files changed, 361 insertions, 0 deletions
diff --git a/SRC/dlasr.f b/SRC/dlasr.f new file mode 100644 index 00000000..7e54bfc7 --- /dev/null +++ b/SRC/dlasr.f @@ -0,0 +1,361 @@ + SUBROUTINE DLASR( SIDE, PIVOT, DIRECT, M, N, C, S, A, LDA ) +* +* -- LAPACK auxiliary routine (version 3.1) -- +* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. +* November 2006 +* +* .. Scalar Arguments .. + CHARACTER DIRECT, PIVOT, SIDE + INTEGER LDA, M, N +* .. +* .. Array Arguments .. + DOUBLE PRECISION A( LDA, * ), C( * ), S( * ) +* .. +* +* Purpose +* ======= +* +* DLASR applies a sequence of plane rotations to a real matrix A, +* from either the left or the right. +* +* When SIDE = 'L', the transformation takes the form +* +* A := P*A +* +* and when SIDE = 'R', the transformation takes the form +* +* A := A*P**T +* +* where P is an orthogonal matrix consisting of a sequence of z plane +* rotations, with z = M when SIDE = 'L' and z = N when SIDE = 'R', +* and P**T is the transpose of P. +* +* When DIRECT = 'F' (Forward sequence), then +* +* P = P(z-1) * ... * P(2) * P(1) +* +* and when DIRECT = 'B' (Backward sequence), then +* +* P = P(1) * P(2) * ... * P(z-1) +* +* where P(k) is a plane rotation matrix defined by the 2-by-2 rotation +* +* R(k) = ( c(k) s(k) ) +* = ( -s(k) c(k) ). +* +* When PIVOT = 'V' (Variable pivot), the rotation is performed +* for the plane (k,k+1), i.e., P(k) has the form +* +* P(k) = ( 1 ) +* ( ... ) +* ( 1 ) +* ( c(k) s(k) ) +* ( -s(k) c(k) ) +* ( 1 ) +* ( ... ) +* ( 1 ) +* +* where R(k) appears as a rank-2 modification to the identity matrix in +* rows and columns k and k+1. +* +* When PIVOT = 'T' (Top pivot), the rotation is performed for the +* plane (1,k+1), so P(k) has the form +* +* P(k) = ( c(k) s(k) ) +* ( 1 ) +* ( ... ) +* ( 1 ) +* ( -s(k) c(k) ) +* ( 1 ) +* ( ... ) +* ( 1 ) +* +* where R(k) appears in rows and columns 1 and k+1. +* +* Similarly, when PIVOT = 'B' (Bottom pivot), the rotation is +* performed for the plane (k,z), giving P(k) the form +* +* P(k) = ( 1 ) +* ( ... ) +* ( 1 ) +* ( c(k) s(k) ) +* ( 1 ) +* ( ... ) +* ( 1 ) +* ( -s(k) c(k) ) +* +* where R(k) appears in rows and columns k and z. The rotations are +* performed without ever forming P(k) explicitly. +* +* Arguments +* ========= +* +* SIDE (input) CHARACTER*1 +* Specifies whether the plane rotation matrix P is applied to +* A on the left or the right. +* = 'L': Left, compute A := P*A +* = 'R': Right, compute A:= A*P**T +* +* PIVOT (input) CHARACTER*1 +* Specifies the plane for which P(k) is a plane rotation +* matrix. +* = 'V': Variable pivot, the plane (k,k+1) +* = 'T': Top pivot, the plane (1,k+1) +* = 'B': Bottom pivot, the plane (k,z) +* +* DIRECT (input) CHARACTER*1 +* Specifies whether P is a forward or backward sequence of +* plane rotations. +* = 'F': Forward, P = P(z-1)*...*P(2)*P(1) +* = 'B': Backward, P = P(1)*P(2)*...*P(z-1) +* +* M (input) INTEGER +* The number of rows of the matrix A. If m <= 1, an immediate +* return is effected. +* +* N (input) INTEGER +* The number of columns of the matrix A. If n <= 1, an +* immediate return is effected. +* +* C (input) DOUBLE PRECISION array, dimension +* (M-1) if SIDE = 'L' +* (N-1) if SIDE = 'R' +* The cosines c(k) of the plane rotations. +* +* S (input) DOUBLE PRECISION array, dimension +* (M-1) if SIDE = 'L' +* (N-1) if SIDE = 'R' +* The sines s(k) of the plane rotations. The 2-by-2 plane +* rotation part of the matrix P(k), R(k), has the form +* R(k) = ( c(k) s(k) ) +* ( -s(k) c(k) ). +* +* A (input/output) DOUBLE PRECISION array, dimension (LDA,N) +* The M-by-N matrix A. On exit, A is overwritten by P*A if +* SIDE = 'R' or by A*P**T if SIDE = 'L'. +* +* LDA (input) INTEGER +* The leading dimension of the array A. LDA >= max(1,M). +* +* ===================================================================== +* +* .. Parameters .. + DOUBLE PRECISION ONE, ZERO + PARAMETER ( ONE = 1.0D+0, ZERO = 0.0D+0 ) +* .. +* .. Local Scalars .. + INTEGER I, INFO, J + DOUBLE PRECISION CTEMP, STEMP, TEMP +* .. +* .. External Functions .. + LOGICAL LSAME + EXTERNAL LSAME +* .. +* .. External Subroutines .. + EXTERNAL XERBLA +* .. +* .. Intrinsic Functions .. + INTRINSIC MAX +* .. +* .. Executable Statements .. +* +* Test the input parameters +* + INFO = 0 + IF( .NOT.( LSAME( SIDE, 'L' ) .OR. LSAME( SIDE, 'R' ) ) ) THEN + INFO = 1 + ELSE IF( .NOT.( LSAME( PIVOT, 'V' ) .OR. LSAME( PIVOT, + $ 'T' ) .OR. LSAME( PIVOT, 'B' ) ) ) THEN + INFO = 2 + ELSE IF( .NOT.( LSAME( DIRECT, 'F' ) .OR. LSAME( DIRECT, 'B' ) ) ) + $ THEN + INFO = 3 + ELSE IF( M.LT.0 ) THEN + INFO = 4 + ELSE IF( N.LT.0 ) THEN + INFO = 5 + ELSE IF( LDA.LT.MAX( 1, M ) ) THEN + INFO = 9 + END IF + IF( INFO.NE.0 ) THEN + CALL XERBLA( 'DLASR ', INFO ) + RETURN + END IF +* +* Quick return if possible +* + IF( ( M.EQ.0 ) .OR. ( N.EQ.0 ) ) + $ RETURN + IF( LSAME( SIDE, 'L' ) ) THEN +* +* Form P * A +* + IF( LSAME( PIVOT, 'V' ) ) THEN + IF( LSAME( DIRECT, 'F' ) ) THEN + DO 20 J = 1, M - 1 + CTEMP = C( J ) + STEMP = S( J ) + IF( ( CTEMP.NE.ONE ) .OR. ( STEMP.NE.ZERO ) ) THEN + DO 10 I = 1, N + TEMP = A( J+1, I ) + A( J+1, I ) = CTEMP*TEMP - STEMP*A( J, I ) + A( J, I ) = STEMP*TEMP + CTEMP*A( J, I ) + 10 CONTINUE + END IF + 20 CONTINUE + ELSE IF( LSAME( DIRECT, 'B' ) ) THEN + DO 40 J = M - 1, 1, -1 + CTEMP = C( J ) + STEMP = S( J ) + IF( ( CTEMP.NE.ONE ) .OR. ( STEMP.NE.ZERO ) ) THEN + DO 30 I = 1, N + TEMP = A( J+1, I ) + A( J+1, I ) = CTEMP*TEMP - STEMP*A( J, I ) + A( J, I ) = STEMP*TEMP + CTEMP*A( J, I ) + 30 CONTINUE + END IF + 40 CONTINUE + END IF + ELSE IF( LSAME( PIVOT, 'T' ) ) THEN + IF( LSAME( DIRECT, 'F' ) ) THEN + DO 60 J = 2, M + CTEMP = C( J-1 ) + STEMP = S( J-1 ) + IF( ( CTEMP.NE.ONE ) .OR. ( STEMP.NE.ZERO ) ) THEN + DO 50 I = 1, N + TEMP = A( J, I ) + A( J, I ) = CTEMP*TEMP - STEMP*A( 1, I ) + A( 1, I ) = STEMP*TEMP + CTEMP*A( 1, I ) + 50 CONTINUE + END IF + 60 CONTINUE + ELSE IF( LSAME( DIRECT, 'B' ) ) THEN + DO 80 J = M, 2, -1 + CTEMP = C( J-1 ) + STEMP = S( J-1 ) + IF( ( CTEMP.NE.ONE ) .OR. ( STEMP.NE.ZERO ) ) THEN + DO 70 I = 1, N + TEMP = A( J, I ) + A( J, I ) = CTEMP*TEMP - STEMP*A( 1, I ) + A( 1, I ) = STEMP*TEMP + CTEMP*A( 1, I ) + 70 CONTINUE + END IF + 80 CONTINUE + END IF + ELSE IF( LSAME( PIVOT, 'B' ) ) THEN + IF( LSAME( DIRECT, 'F' ) ) THEN + DO 100 J = 1, M - 1 + CTEMP = C( J ) + STEMP = S( J ) + IF( ( CTEMP.NE.ONE ) .OR. ( STEMP.NE.ZERO ) ) THEN + DO 90 I = 1, N + TEMP = A( J, I ) + A( J, I ) = STEMP*A( M, I ) + CTEMP*TEMP + A( M, I ) = CTEMP*A( M, I ) - STEMP*TEMP + 90 CONTINUE + END IF + 100 CONTINUE + ELSE IF( LSAME( DIRECT, 'B' ) ) THEN + DO 120 J = M - 1, 1, -1 + CTEMP = C( J ) + STEMP = S( J ) + IF( ( CTEMP.NE.ONE ) .OR. ( STEMP.NE.ZERO ) ) THEN + DO 110 I = 1, N + TEMP = A( J, I ) + A( J, I ) = STEMP*A( M, I ) + CTEMP*TEMP + A( M, I ) = CTEMP*A( M, I ) - STEMP*TEMP + 110 CONTINUE + END IF + 120 CONTINUE + END IF + END IF + ELSE IF( LSAME( SIDE, 'R' ) ) THEN +* +* Form A * P' +* + IF( LSAME( PIVOT, 'V' ) ) THEN + IF( LSAME( DIRECT, 'F' ) ) THEN + DO 140 J = 1, N - 1 + CTEMP = C( J ) + STEMP = S( J ) + IF( ( CTEMP.NE.ONE ) .OR. ( STEMP.NE.ZERO ) ) THEN + DO 130 I = 1, M + TEMP = A( I, J+1 ) + A( I, J+1 ) = CTEMP*TEMP - STEMP*A( I, J ) + A( I, J ) = STEMP*TEMP + CTEMP*A( I, J ) + 130 CONTINUE + END IF + 140 CONTINUE + ELSE IF( LSAME( DIRECT, 'B' ) ) THEN + DO 160 J = N - 1, 1, -1 + CTEMP = C( J ) + STEMP = S( J ) + IF( ( CTEMP.NE.ONE ) .OR. ( STEMP.NE.ZERO ) ) THEN + DO 150 I = 1, M + TEMP = A( I, J+1 ) + A( I, J+1 ) = CTEMP*TEMP - STEMP*A( I, J ) + A( I, J ) = STEMP*TEMP + CTEMP*A( I, J ) + 150 CONTINUE + END IF + 160 CONTINUE + END IF + ELSE IF( LSAME( PIVOT, 'T' ) ) THEN + IF( LSAME( DIRECT, 'F' ) ) THEN + DO 180 J = 2, N + CTEMP = C( J-1 ) + STEMP = S( J-1 ) + IF( ( CTEMP.NE.ONE ) .OR. ( STEMP.NE.ZERO ) ) THEN + DO 170 I = 1, M + TEMP = A( I, J ) + A( I, J ) = CTEMP*TEMP - STEMP*A( I, 1 ) + A( I, 1 ) = STEMP*TEMP + CTEMP*A( I, 1 ) + 170 CONTINUE + END IF + 180 CONTINUE + ELSE IF( LSAME( DIRECT, 'B' ) ) THEN + DO 200 J = N, 2, -1 + CTEMP = C( J-1 ) + STEMP = S( J-1 ) + IF( ( CTEMP.NE.ONE ) .OR. ( STEMP.NE.ZERO ) ) THEN + DO 190 I = 1, M + TEMP = A( I, J ) + A( I, J ) = CTEMP*TEMP - STEMP*A( I, 1 ) + A( I, 1 ) = STEMP*TEMP + CTEMP*A( I, 1 ) + 190 CONTINUE + END IF + 200 CONTINUE + END IF + ELSE IF( LSAME( PIVOT, 'B' ) ) THEN + IF( LSAME( DIRECT, 'F' ) ) THEN + DO 220 J = 1, N - 1 + CTEMP = C( J ) + STEMP = S( J ) + IF( ( CTEMP.NE.ONE ) .OR. ( STEMP.NE.ZERO ) ) THEN + DO 210 I = 1, M + TEMP = A( I, J ) + A( I, J ) = STEMP*A( I, N ) + CTEMP*TEMP + A( I, N ) = CTEMP*A( I, N ) - STEMP*TEMP + 210 CONTINUE + END IF + 220 CONTINUE + ELSE IF( LSAME( DIRECT, 'B' ) ) THEN + DO 240 J = N - 1, 1, -1 + CTEMP = C( J ) + STEMP = S( J ) + IF( ( CTEMP.NE.ONE ) .OR. ( STEMP.NE.ZERO ) ) THEN + DO 230 I = 1, M + TEMP = A( I, J ) + A( I, J ) = STEMP*A( I, N ) + CTEMP*TEMP + A( I, N ) = CTEMP*A( I, N ) - STEMP*TEMP + 230 CONTINUE + END IF + 240 CONTINUE + END IF + END IF + END IF +* + RETURN +* +* End of DLASR +* + END |