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LAPACK
3.7.0
LAPACK: Linear Algebra PACKage
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subroutine dlarz | ( | character | SIDE, |
integer | M, | ||
integer | N, | ||
integer | L, | ||
double precision, dimension( * ) | V, | ||
integer | INCV, | ||
double precision | TAU, | ||
double precision, dimension( ldc, * ) | C, | ||
integer | LDC, | ||
double precision, dimension( * ) | WORK | ||
) |
DLARZ applies an elementary reflector (as returned by stzrzf) to a general matrix.
Download DLARZ + dependencies [TGZ] [ZIP] [TXT]
DLARZ applies a real elementary reflector H to a real M-by-N matrix C, from either the left or the right. H is represented in the form H = I - tau * v * v**T where tau is a real scalar and v is a real vector. If tau = 0, then H is taken to be the unit matrix. H is a product of k elementary reflectors as returned by DTZRZF.
[in] | SIDE | SIDE is CHARACTER*1 = 'L': form H * C = 'R': form C * H |
[in] | M | M is INTEGER The number of rows of the matrix C. |
[in] | N | N is INTEGER The number of columns of the matrix C. |
[in] | L | L is INTEGER The number of entries of the vector V containing the meaningful part of the Householder vectors. If SIDE = 'L', M >= L >= 0, if SIDE = 'R', N >= L >= 0. |
[in] | V | V is DOUBLE PRECISION array, dimension (1+(L-1)*abs(INCV)) The vector v in the representation of H as returned by DTZRZF. V is not used if TAU = 0. |
[in] | INCV | INCV is INTEGER The increment between elements of v. INCV <> 0. |
[in] | TAU | TAU is DOUBLE PRECISION The value tau in the representation of H. |
[in,out] | C | C is DOUBLE PRECISION array, dimension (LDC,N) On entry, the M-by-N matrix C. On exit, C is overwritten by the matrix H * C if SIDE = 'L', or C * H if SIDE = 'R'. |
[in] | LDC | LDC is INTEGER The leading dimension of the array C. LDC >= max(1,M). |
[out] | WORK | WORK is DOUBLE PRECISION array, dimension (N) if SIDE = 'L' or (M) if SIDE = 'R' |
Definition at line 147 of file dlarz.f.