?syr

Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

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ID 766686

Date 10/15/2026

Version

Public

?syr

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

Syntax

call csyr(uplo, n, alpha, x, incx, a, lda)
call zsyr(uplo, n, alpha, x, incx, a, lda)

Include Files

mkl.fi

Description

csyr zsyr

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 (Performs a rank-1 update of a symmetric matrix.) in Chapter “BLAS and Sparse BLAS Routines” ).

Input Parameters

uplo

CHARACTER*1 . 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

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

alpha: COMPLEX for csyr DOUBLE COMPLEX for zsyr Specifies the scalar alpha .
x: COMPLEX for csyr DOUBLE COMPLEX for zsyr Array, size at least (1 + (n - 1)*abs(incx)) . Before entry, the incremented array x must contain the n -element vector x .

incx

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

a: COMPLEX for csyr DOUBLE COMPLEX for zsyr 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

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) .

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.

info

INTEGER .

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.

Return Values

No return value, info is an Output Parameter.

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Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

?syr

Syntax

Include Files

Description

Input Parameters

Output Parameters

Return Values