SLARFY
Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd..
November 2006
November 2006
Purpose
SLARFY applies an elementary reflector, or Householder matrix, H,
to an n x n symmetric matrix C, from both the left and the right.
H is represented in the form
H = I - tau * v * v'
where tau is a scalar and v is a vector.
If tau is zero, then H is taken to be the unit matrix.
to an n x n symmetric matrix C, from both the left and the right.
H is represented in the form
H = I - tau * v * v'
where tau is a scalar and v is a vector.
If tau is zero, then H is taken to be the unit matrix.
Arguments
| UPLO |
(input) CHARACTER*1
Specifies whether the upper or lower triangular part of the
symmetric matrix C is stored. = 'U': Upper triangle = 'L': Lower triangle |
| N |
(input) INTEGER
The number of rows and columns of the matrix C. N >= 0.
|
| V |
(input) REAL array, dimension
(1 + (N-1)*abs(INCV))
The vector v as described above. |
| INCV |
(input) INTEGER
The increment between successive elements of v. INCV must
not be zero. |
| TAU |
(input) REAL
The value tau as described above.
|
| C |
(input/output) REAL array, dimension (LDC, N)
On entry, the matrix C.
On exit, C is overwritten by H * C * H'. |
| LDC |
(input) INTEGER
The leading dimension of the array C. LDC >= max( 1, N ).
|
| WORK |
(workspace) REAL array, dimension (N)
|