![]() |
LAPACK
3.7.0
LAPACK: Linear Algebra PACKage
|
subroutine dorm2l | ( | character | SIDE, |
character | TRANS, | ||
integer | M, | ||
integer | N, | ||
integer | K, | ||
double precision, dimension( lda, * ) | A, | ||
integer | LDA, | ||
double precision, dimension( * ) | TAU, | ||
double precision, dimension( ldc, * ) | C, | ||
integer | LDC, | ||
double precision, dimension( * ) | WORK, | ||
integer | INFO | ||
) |
DORM2L multiplies a general matrix by the orthogonal matrix from a QL factorization determined by sgeqlf (unblocked algorithm).
Download DORM2L + dependencies [TGZ] [ZIP] [TXT]
DORM2L overwrites the general real m by n matrix C with Q * C if SIDE = 'L' and TRANS = 'N', or Q**T * C if SIDE = 'L' and TRANS = 'T', or C * Q if SIDE = 'R' and TRANS = 'N', or C * Q**T if SIDE = 'R' and TRANS = 'T', where Q is a real orthogonal matrix defined as the product of k elementary reflectors Q = H(k) . . . H(2) H(1) as returned by DGEQLF. Q is of order m if SIDE = 'L' and of order n if SIDE = 'R'.
[in] | SIDE | SIDE is CHARACTER*1 = 'L': apply Q or Q**T from the Left = 'R': apply Q or Q**T from the Right |
[in] | TRANS | TRANS is CHARACTER*1 = 'N': apply Q (No transpose) = 'T': apply Q**T (Transpose) |
[in] | M | M is INTEGER The number of rows of the matrix C. M >= 0. |
[in] | N | N is INTEGER The number of columns of the matrix C. N >= 0. |
[in] | K | K is INTEGER The number of elementary reflectors whose product defines the matrix Q. If SIDE = 'L', M >= K >= 0; if SIDE = 'R', N >= K >= 0. |
[in] | A | A is DOUBLE PRECISION array, dimension (LDA,K) The i-th column must contain the vector which defines the elementary reflector H(i), for i = 1,2,...,k, as returned by DGEQLF in the last k columns of its array argument A. A is modified by the routine but restored on exit. |
[in] | LDA | LDA is INTEGER The leading dimension of the array A. If SIDE = 'L', LDA >= max(1,M); if SIDE = 'R', LDA >= max(1,N). |
[in] | TAU | TAU is DOUBLE PRECISION array, dimension (K) TAU(i) must contain the scalar factor of the elementary reflector H(i), as returned by DGEQLF. |
[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 Q*C or Q**T*C or C*Q**T or C*Q. |
[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', (M) if SIDE = 'R' |
[out] | INFO | INFO is INTEGER = 0: successful exit < 0: if INFO = -i, the i-th argument had an illegal value |
Definition at line 161 of file dorm2l.f.