DORM2L
Purpose
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'.
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'.
Arguments
| SIDE |
(input) CHARACTER*1
= 'L': apply Q or Q**T from the Left
= 'R': apply Q or Q**T from the Right |
| TRANS |
(input) CHARACTER*1
= 'N': apply Q (No transpose)
= 'T': apply Q**T (Transpose) |
| M |
(input) INTEGER
The number of rows of the matrix C. M >= 0.
|
| N |
(input) INTEGER
The number of columns of the matrix C. N >= 0.
|
| K |
(input) INTEGER
The number of elementary reflectors whose product defines
the matrix Q. If SIDE = 'L', M >= K >= 0; if SIDE = 'R', N >= K >= 0. |
| A |
(input) 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. |
| LDA |
(input) INTEGER
The leading dimension of the array A.
If SIDE = 'L', LDA >= max(1,M); if SIDE = 'R', LDA >= max(1,N). |
| TAU |
(input) DOUBLE PRECISION array, dimension (K)
TAU(i) must contain the scalar factor of the elementary
reflector H(i), as returned by DGEQLF. |
| C |
(input/output) 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. |
| LDC |
(input) INTEGER
The leading dimension of the array C. LDC >= max(1,M).
|
| WORK |
(workspace) DOUBLE PRECISION array, dimension
(N) if SIDE = 'L',
(M) if SIDE = 'R' |
| INFO |
(output) INTEGER
= 0: successful exit
< 0: if INFO = -i, the i-th argument had an illegal value |