?la_heamv

Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

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ID 766686

Date 4/28/2026

Version

Public

?la_heamv

Computes a matrix-vector product using a Hermitian indefinite matrix to calculate error bounds.

Syntax

call cla_heamv ( uplo , n , alpha , a , lda , x , incx , beta , y , incy )

call zla_heamv ( uplo , n , alpha , a , lda , x , incx , beta , y , incy )

Include Files

mkl.fi

Description

The ?la_heamv 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 cla_heamv DOUBLE PRECISION for zla_heamv Specifies the scalar alpha .
a: COMPLEX for cla_heamv DOUBLE COMPLEX for zla_heamv 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: COMPLEX for cla_heamv DOUBLE COMPLEX for zla_heamv 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 cla_heamv DOUBLE PRECISION for zla_heamv Specifies the scalar beta . When beta is zero, you do not need to set y on input.
y: REAL for cla_heamv DOUBLE PRECISION for zla_heamv 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 .

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Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

?la_heamv

Syntax

Include Files

Description

Input Parameters

Output Parameters