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SUBROUTINE DLATZM( SIDE, M, N, V, INCV, TAU, C1, C2, LDC, WORK )
* * -- LAPACK routine (version 3.3.1) -- * -- LAPACK is a software package provided by Univ. of Tennessee, -- * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- * -- April 2011 -- * * .. 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 * * Purpose * ======= * * This routine is deprecated and has been replaced by routine DORMRZ.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**T, 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**T * C2)**T * 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**T * [ 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**T] * 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 |