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template<typename T, typename Ta>
void la_heamv(integer *uplo, integer *n, Ta *alpha, T *a, integer *lda, T *x, integer *incx, Ta *beta, Ta *y, integer *incy)# LA_HEAMV computes a matrix-vector product using a Hermitian indefinite matrix to calculate error bounds.
Purpose:
LA_HEAMV performs the matrix-vector operation y := alpha*abs(A)*abs(x) + beta*abs(y), where alpha and beta are scalars, x and y are vectors and A is an n by n symmetric matrix. This function is primarily used in calculating error bounds. To protect against underflow during evaluation, components in the resulting vector are perturbed away from zero by (N+1) times the underflow threshold. To prevent unnecessarily large errors for block-structure embedded in general matrices, "symbolically" zero components are not perturbed. A zero entry is considered "symbolic" if all multiplications involved in computing that entry have at least one zero multiplicand.
- Parameters:
UPLO – [in]
UPLO is INTEGER
On entry, UPLO specifies whether the upper or lower triangular part of the array A is to be referenced as follows:
UPLO = BLAS_UPPER Only the upper triangular part of A is to be referenced.
UPLO = BLAS_LOWER Only the lower triangular part of A is to be referenced.
Unchanged on exit.N – [in]
N is INTEGER
On entry, N specifies the number of columns of the matrix A. N must be at least zero.
Unchanged on exit.ALPHA – [in]
ALPHA is REAL .
On entry, ALPHA specifies the scalar alpha. Unchanged on exit.
A – [in]
A is COMPLEX array, dimension (LDA, n).
Before entry, the leading m by n part of the array A must contain the matrix of coefficients.
Unchanged on exit.LDA – [in]
LDA is INTEGER
On entry, LDA specifies the first dimension of A as declared in the calling (sub) program. LDA must be at least fla_max(1, n).
Unchanged on exit.X – [in]
X is COMPLEX array, dimension (1 + (n - 1)*abs(INCX))
Before entry, the incremented array X must contain the vector x.
Unchanged on exit.INCX – [in]
INCX is INTEGER
On entry, INCX specifies the increment for the elements of X. INCX must not be zero.
Unchanged on exit.BETA – [in]
BETA is REAL.
On entry, BETA specifies the scalar beta. When BETA is supplied as zero then Y need not be set on input. Unchanged on exit.
Y – [inout]
Y is REAL array, dimension (1 + (n - 1)*abs(INCY))
Before entry with BETA non-zero, the incremented array Y must contain the vector y. On exit, Y is overwritten by the updated vector y.
INCY – [in]
INCY is INTEGER
On entry, INCY specifies the increment for the elements of Y. INCY must not be zero.
Unchanged on exit.