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# cblas_zher2(_:_:_:_:_:_:_:_:_:_:)

Hermitian rank 2 update: adds the product of a scaling factor, vector `X`, and the conjugate transpose of vector `Y` to the product of the conjugate of the scaling factor, vector `Y`, and the conjugate transpose of vector `X`, and adds the result to matrix `A`.

```
func cblas_zher2(_ ORDER: CBLAS_ORDER, _ UPLO: CBLAS_UPLO, _ N: __LAPACK_int, _ ALPHA: OpaquePointer, _ X: OpaquePointer?, _ INCX: __LAPACK_int, _ Y: OpaquePointer?, _ INCY: __LAPACK_int, _ A: OpaquePointer?, _ LDA: __LAPACK_int)
```

## Parameters

`ORDER`

Specifies row-major (C) or column-major (Fortran) data ordering.

`UPLO`

Specifies whether to use the upper or lower triangle from the matrix. Valid values are `'U'` or `'L'`.

`N`

The order of matrix `A`.

`ALPHA`

The scaling factor `α`.

`X`

Vector `X`.

`INCX`

Stride within `X`. For example, if `incX` is 7, every 7th element is used.

`Y`

Vector `Y`.

`INCY`

Stride within `Y`. For example, if `incY` is 7, every 7th element is used.

`A`

Matrix `A`.

`LDA`

The leading dimension of matrix `A`.

## Discussion

Computes `A←αX*conjg(Y') + conjg(α)*Y*conjg(X') + A`.

> Important:
> Apple provides the BLAS and LAPACK libraries under the Accelerate framework to be in line with LAPACK 3.9.1. Starting with iOS 26, iPadOS 26, macOS 26, tvOS 26, visionOS 26, and watchOS 26, the libraries are in line with LAPACK 3.12.0. These new interfaces provide additional functionality, as well as a new ILP64 interface. To use the new interfaces, define `ACCELERATE_NEW_LAPACK` before including the Accelerate or vecLib headers. For ILP64 interfaces, also define `ACCELERATE_LAPACK_ILP64`. For Swift projects, specify `ACCELERATE_NEW_LAPACK=1` and `ACCELERATE_LAPACK_ILP64=1` as preprocessor macros in Xcode build settings under Apple Clang - Preprocessing > Preprocessor Macros.

---

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