?syr

Developer Reference for Intel® oneAPI Math Kernel Library for C

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ID 766684

Date 3/22/2024

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?syr

Performs the symmetric rank-1 update of a complex symmetric matrix.

Syntax

lapack_int LAPACKE_csyr (int matrix_layout, char uplo, lapack_int n, lapack_complex_float alpha, const lapack_complex_float * x, lapack_int incx, lapack_complex_float * a, lapack_int lda);

lapack_int LAPACKE_zsyr (int matrix_layout, char uplo, lapack_int n, lapack_complex_double alpha, const lapack_complex_double * x, lapack_int incx, lapack_complex_double * a, lapack_int lda);

Include Files

mkl.h

Description

The routine performs the symmetric rank 1 operation defined as

a := alpha*x*x^H + a,

where:

alpha is a complex scalar.
x is an n-element complex vector.
a is an n-by-n complex symmetric matrix.

These routines have their real equivalents in BLAS (see ?syr in Chapter "BLAS and Sparse BLAS Routines").

Input Parameters

matrix_layout

Specifies whether matrix storage layout is row major (LAPACK_ROW_MAJOR) or column major (LAPACK_COL_MAJOR).

uplo

Specifies whether the upper or lower triangular part of the array a is used:

If uplo = 'U' or 'u', then the upper triangular part of the array a is used.

If uplo = 'L' or 'l', then the lower triangular part of the array a is used.

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. The value of incx must not be zero.

a

Array, size max(1, lda*n). Before entry with uplo = 'U' or 'u', the leading n-by-n upper triangular part of the array a must contain the upper triangular part of the symmetric matrix and the strictly lower triangular part of a is not referenced.

Before entry with uplo = 'L' or 'l', the leading n-by-n lower triangular part of the array a must contain the lower triangular part of the symmetric matrix and the strictly upper triangular part of a is not referenced.

lda

Specifies the leading dimension of a as declared in the calling (sub)program. The value of lda must be at least max(1,n).

Output Parameters

a

With uplo = 'U' or 'u', the upper triangular part of the array a is overwritten by the upper triangular part of the updated matrix.

With uplo = 'L' or 'l', the lower triangular part of the array a is overwritten by the lower triangular part of the updated matrix.

Return Values

This function returns a value info.

If info = 0, the execution is successful.

If info < 0, the i-th parameter had an illegal value.

If info = -1011, memory allocation error occurred.

Parent topic: LAPACK Auxiliary Routines

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Developer Reference for Intel® oneAPI Math Kernel Library for C

?syr

Syntax

Include Files

Description

Input Parameters

Output Parameters

Return Values