Visible to Intel only — GUID: GUID-4799FB07-6F1A-4DAC-8CBE-D441F1AF28B5
Visible to Intel only — GUID: GUID-4799FB07-6F1A-4DAC-8CBE-D441F1AF28B5
?larfy
Applies an elementary reflector, or Householder matrix, H, to an n by n symmetric or Hermitian matrix C, from both the left and the right.
call slarfy(uplo, n, v, incv, tau, C, ldc, work)
call dlarfy(uplo, n, v, incv, tau, C, ldc, work)
call clarfy(uplo, n, v, incv, tau, C, ldc, work)
call zlarfy(uplo, n, v, incv, tau, C, ldc, work)
Description
?larfy applies an elementary reflector, or Householder matrix, H, to an n by n symmetric or Hermitian matrix C, from both the left and the right. H is represented in the form H = I - tau * v * vT (for real flavors) or H = I - tau * v * vH (for complex flavors), where tau is a scalar and v is a vector. If tau is zero, H is taken to be the unit matrix.
Input Parameters
- uplo
-
CHARACTER*1
Specifies whether the upper or lower triangular part of the symmetric or Hermitian matrix C is stored.
- = 'U': Upper triangular part of C is stored.
- = 'L': Lower triangular part of C is stored.
- n
-
INTEGER
The number of rows and columns of the matrix C. n ≥ 0.
- v
-
REAL for slarfy
DOUBLE PRECISION for dlarfy
COMPLEX for clarfy
COMPLEX*16 for zlarfy
Array, dimension (1 + (n-1)*abs(incv)). The vector v as described above.
- incv
-
INTEGER
The increment between successive elements of v. incv must not be zero.
- tau
-
REAL for slarfy
DOUBLE PRECISION for dlarfy
COMPLEX for clarfy
COMPLEX*16 for zlarfy
The value tau as described above.
- C
-
REAL for slarfy
DOUBLE PRECISION for dlarfy
COMPLEX for clarfy
COMPLEX*16 for zlarfy
Array, dimension (ldc, n). On entry, the matrix C.
- ldc
-
INTEGER
The leading dimension of the array C. ldc ≥ max( 1, n ).
Output Parameters
- C
-
REAL for slarfy
DOUBLE PRECISION for dlarfy
COMPLEX for clarfy
COMPLEX*16 for zlarfy
On exit, C is overwritten by H * C * HT (for real flavors) or H * C * HH (for complex flavors).
- work
-
REAL for slarfy
DOUBLE PRECISION for dlarfy
COMPLEX for clarfy
COMPLEX*16 for zlarfy
Array, dimension (n).