Visible to Intel only — GUID: GUID-121CEA33-9EAD-463F-BBE3-9DAD63390F1A
Visible to Intel only — GUID: GUID-121CEA33-9EAD-463F-BBE3-9DAD63390F1A
?la_syamv
Computes a matrix-vector product using a symmetric indefinite matrix to calculate error bounds.
Syntax
call sla_syamv(uplo, n, alpha, a, lda, x, incx, beta, y, incy)
call dla_syamv(uplo, n, alpha, a, lda, x, incx, beta, y, incy)
call cla_syamv(uplo, n, alpha, a, lda, x, incx, beta, y, incy)
call zla_syamv(uplo, n, alpha, a, lda, x, incx, beta, y, incy)
Include Files
- mkl.fi
Description
The ?la_syamv routines perform a matrix-vector operation defined as
y := alpha*abs(A)*abs(x) + beta*abs(y),
where:
alpha and beta are scalars,
x and y are vectors,
A is an n-by-n Hermitian matrix.
This function is primarily used in calculating error bounds. To protect against underflow during evaluation, the function perturbs components in the resulting vector away from zero by (n + 1) times the underflow threshold. To prevent unnecessarily large errors for block structure embedded in general matrices, the function does not perturb symbolically zero components. A zero entry is considered symbolic if all multiplications involved in computing that entry have at least one zero multiplicand.
Input Parameters
- uplo
-
CHARACTER*1.
Specifies whether the upper or lower triangular part of the array A is to be referenced:
If uplo = 'BLAS_UPPER', only the upper triangular part of A is to be referenced,
If uplo = 'BLAS_LOWER', only the lower triangular part of A is to be referenced.
- n
-
INTEGER. Specifies the number of rows and columns of the matrix A. The value of n must be at least zero.
- alpha
-
REAL for sla_syamv and cla_syamv
DOUBLE PRECISION for dla_syamv and zla_syamv.
Specifies the scalar alpha.
- a
-
REAL for sla_syamv
DOUBLE PRECISION for dla_syamv
COMPLEX for cla_syamv
DOUBLE COMPLEX for zla_syamv.
Array, DIMENSION(lda, *). Before entry, the leading m-by-n part of the array a must contain the matrix of coefficients. The second dimension of a must be at least max(1,n).
- 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).
- x
-
REAL for sla_syamv
DOUBLE PRECISION for dla_syamv
COMPLEX for cla_syamv
DOUBLE COMPLEX for zla_syamv.
Array, DIMENSION at least (1+(n-1)*abs(incx)). Before entry, the incremented array x must contain the vector X.
- incx
-
INTEGER. Specifies the increment for the elements of x.
The value of incx must be non-zero.
- beta
-
REAL for sla_syamv and cla_syamv
DOUBLE PRECISION for dla_syamv and zla_syamv
Specifies the scalar beta. When beta is zero, you do not need to set y on input.
- y
-
REAL for sla_syamv and cla_syamv
DOUBLE PRECISION for dla_syamv and zla_syamv
Array, DIMENSION at least (1 +(n - 1)*abs(incy)) otherwise. Before entry with non-zero beta, the incremented array y must contain the vector Y.
- incy
-
INTEGER. Specifies the increment for the elements of y.
The value of incy must be non-zero.
Output Parameters
- y
-
Updated vector Y.