cblas_?hpr

Performs a rank-1 update of a Hermitian packed matrix.

Syntax

void cblas_chpr (const CBLAS_LAYOUT Layout, const CBLAS_UPLO uplo, const MKL_INT n, const float alpha, const void *x, const MKL_INT incx, void *ap);

void cblas_zhpr (const CBLAS_LAYOUT Layout, const CBLAS_UPLO uplo, const MKL_INT n, const double alpha, const void *x, const MKL_INT incx, void *ap);

Include Files

  • mkl.h

Description

The ?hpr 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, supplied in packed form.

Input Parameters

Layout

Specifies whether two-dimensional array storage is row-major (CblasRowMajor) or column-major (CblasColMajor).

uplo

Specifies whether the upper or lower triangular part of the matrix A is supplied in the packed array ap.

If uplo = CblasUpper, the upper triangular part of the matrix A is supplied in the packed array ap .

If uplo = CblasLower, the low triangular part of the matrix A is supplied in the packed array ap .

n

Specifies the order of the matrix A. The value of n must be at least zero.

alpha

Specifies the scalar alpha.

x

Array, size at least (1 + (n - 1)*abs(incx)). Before entry, the incremented array x must contain the n-element vector x.

incx

Specifies the increment for the elements of x. incx must not be zero.

ap

Array, size at least ((n*(n + 1))/2).

For Layout = CblasColMajor:

Before entry with uplo = CblasUpper, the array ap must contain the upper triangular part of the Hermitian matrix packed sequentially, column-by-column, so that ap[0] contains A1, 1, ap[1] and ap[2] contain A1, 2 and A2, 2 respectively, and so on.

Before entry with uplo = CblasLower, the array ap must contain the lower triangular part of the Hermitian matrix packed sequentially, column-by-column, so that ap[0] contains A1, 1, ap[1] and ap[2] contain A2, 1 and A3, 1 respectively, and so on.

For Layout = CblasRowMajor:

Before entry with uplo = CblasUpper, the array ap must contain the upper triangular part of the Hermitian matrix packed sequentially, row-by-row, ap[0] contains A1, 1, ap[1] and ap[2] contain A1, 2 and A1, 3 respectively, and so on.

Before entry with uplo = CblasLower, the array ap must contain the lower triangular part of the Hermitian matrix packed sequentially, row-by-row, so that ap[0] contains A1, 1, ap[1] and ap[2] contain A2, 1 and A2, 2 respectively, and so on.

The imaginary parts of the diagonal elements need not be set and are assumed to be zero.

Output Parameters

ap

With uplo = CblasUpper, overwritten by the upper triangular part of the updated matrix.

With uplo = CblasLower, overwritten by the lower triangular part of the updated matrix.

The imaginary parts of the diagonal elements are set to zero.

For more complete information about compiler optimizations, see our Optimization Notice.
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