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syr2

Computes a rank-2 update of a symmetric matrix.

Description

The syr2 routines compute two scalar-vector-vector products, add them and add the result to a matrix, with a symmetric matrix. The operation is defined as:

A \leftarrow alpha*x*y^T + alpha*y*x^T + A

where:

  • alpha is a scalar

  • A is n x n symmetric matrix

  • x and y are vectors of length n

syr2 supports the following precisions:

T

float

double

syr2 (Buffer Version)

Syntax

namespace oneapi::mkl::blas::column_major {
    void syr2(sycl::queue &queue,
              oneapi::mkl::uplo upper_lower,
              std::int64_t n,
              T alpha,
              sycl::buffer<T,1> &x,
              std::int64_t incx,
              sycl::buffer<T,1> &y,
              std::int64_t incy,
              sycl::buffer<T,1> &a,
              std::int64_t lda)
}

namespace oneapi::mkl::blas::row_major {
    void syr2(sycl::queue &queue,
              oneapi::mkl::uplo upper_lower,
              std::int64_t n,
              T alpha,
              sycl::buffer<T,1> &x,
              std::int64_t incx,
              sycl::buffer<T,1> &y,
              std::int64_t incy,
              sycl::buffer<T,1> &a,
              std::int64_t lda)
}

Input Parameters

queue

The queue where the routine should be executed.

upper_lower

Specifies whether matrix A is upper or lower triangular. See Data Types for more details.

n

Number of columns of matrix A. Must be at least zero.

alpha

Scaling factor for the matrix-vector product.

x

Buffer holding input vector x. Size of the buffer must be at least (1 + (n - 1)*abs(incx)). See Matrix Storage for more details.

incx

Stride of vector x.

y

Buffer holding input/output vector y. Size of the buffer must be at least (1 + (n - 1)*abs(incy)). See Matrix Storage for more details.

incy

Stride of vector y.

a

Buffer holding input matrix A. Size of the buffer must be at least lda * n. See Matrix Storage for more details.

lda

Leading dimension of matrix A. Must be at least n and positive.

Output Parameters

a

Buffer holding updated upper triangular part of the symmetric matrix A if upper_lower=upper, or updated lower triangular part of the symmetric matrix A if upper_lower=lower.

syr2 (USM Version)

Syntax

namespace oneapi::mkl::blas::column_major {
    sycl::event syr2(sycl::queue &queue,
                     oneapi::mkl::uplo upper_lower,
                     std::int64_t n,
                     T alpha,
                     const T *x,
                     std::int64_t incx,
                     const T *y,
                     std::int64_t incy,
                     T *a,
                     std::int64_t lda,
                     const std::vector<sycl::event> &dependencies = {})
}

namespace oneapi::mkl::blas::row_major {
    sycl::event syr2(sycl::queue &queue,
                     oneapi::mkl::uplo upper_lower,
                     std::int64_t n,
                     T alpha,
                     const T *x,
                     std::int64_t incx,
                     const T *y,
                     std::int64_t incy,
                     T *a,
                     std::int64_t lda,
                     const std::vector<sycl::event> &dependencies = {})
}

Input Parameters

queue

The queue where the routine should be executed.

upper_lower

Specifies whether matrix A is upper or lower triangular. See Data Types for more details.

n

Number of columns of matrix A. Must be at least zero.

alpha

Scaling factor for the matrix-vector product.

x

Pointer to input vector x. Size of the array holding input vector x must be at least (1 + (n - 1)*abs(incx)). See Matrix Storage for more details.

incx

Stride of vector x.

y

Pointer to input/output vector y. Size of the array holding input/output vector y must be at least (1 + (n - 1)*abs(incy)). See Matrix Storage for more details.

incy

Stride of vector y.

a

Pointer to input matrix A. Size of the array holding input matrix A must be at least lda * n. See Matrix Storage for more details.

lda

Leading dimension of matrix A. Must be at least n and positive.

dependencies

List of events to wait for before starting computation, if any. If omitted, defaults to no dependencies.

Output Parameters

a

Pointer to updated upper triangular part of the symmetric matrix A if upper_lower=upper, or updated lower triangular part of the symmetric matrix A if upper_lower=lower.

Return Values

Output event to wait on to ensure computation is complete.

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