Visible to Intel only — GUID: GUID-46B4933C-6EE4-40D4-AD99-AE0F32E84ECE
Visible to Intel only — GUID: GUID-46B4933C-6EE4-40D4-AD99-AE0F32E84ECE
?her
Performs a rank-1 update of a Hermitian matrix.
Syntax
call cher(uplo, n, alpha, x, incx, a, lda)
call zher(uplo, n, alpha, x, incx, a, lda)
call her(a, x [,uplo] [, alpha])
Include Files
- mkl.fi, blas.f90
Description
The ?her routines perform a matrix-vector operation defined as
A := alpha*x*conjg(x') + A,
where:
alpha is a real scalar,
x is an n-element vector,
A is an n-by-n Hermitian matrix.
Input Parameters
- uplo
-
CHARACTER*1. Specifies whether the upper or lower triangular part of the array a is used.
If uplo = 'U' or 'u', then the upper triangular of the array a is used.
If uplo = 'L' or 'l', then the low triangular of the array a is used.
- n
-
INTEGER. Specifies the order of the matrix A. The value of n must be at least zero.
- alpha
-
REAL for cher
DOUBLE PRECISION for zher
Specifies the scalar alpha.
- x
-
COMPLEX for cher
DOUBLE COMPLEX for zher
Array, dimension at least (1 + (n - 1)*abs(incx)). Before entry, the incremented array x must contain the n-element vector x.
- incx
-
INTEGER. Specifies the increment for the elements of x.
The value of incx must not be zero.
- a
-
COMPLEX for cher
DOUBLE COMPLEX for zher
Array, size (lda, n).
Before entry with uplo = 'U' or 'u', the leading n-by-n upper triangular part of the array a must contain the upper triangular part of the Hermitian matrix and the strictly lower triangular part of a is not referenced.
Before entry with uplo = 'L' or 'l', the leading n-by-n lower triangular part of the array a must contain the lower triangular part of the Hermitian matrix and the strictly upper triangular part of a is not referenced.
The imaginary parts of the diagonal elements need not be set and are assumed to be zero.
- lda
-
INTEGER. Specifies the leading dimension of a as declared in the calling (sub)program. The value of lda must be at least max(1, n).
Output Parameters
- a
-
With uplo = 'U' or 'u', the upper triangular part of the array a is overwritten by the upper triangular part of the updated matrix.
With uplo = 'L' or 'l', the lower triangular part of the array a is overwritten by the lower triangular part of the updated matrix.
If alpha is zero, matrix A is unchanged; otherwise, the imaginary parts of the diagonal elements are set to zero.
BLAS 95 Interface Notes
Routines in Fortran 95 interface have fewer arguments in the calling sequence than their FORTRAN 77 counterparts. For general conventions applied to skip redundant or reconstructible arguments, see BLAS 95 Interface Conventions.
Specific details for the routine her interface are the following:
- a
-
Holds the matrix A of size (n,n).
- x
-
Holds the vector with the number of elements n.
- uplo
-
Must be 'U' or 'L'. The default value is 'U'.
- alpha
-
The default value is 1.