---
title: "cblas_chpr2(_:_:_:_:_:_:_:_:_:)"
framework: accelerate
role: symbol
role_heading: Function
path: "accelerate/cblas_chpr2(_:_:_:_:_:_:_:_:_:)"
---

# cblas_chpr2(_:_:_:_:_:_:_:_:_:)

Multiplies a vector times the conjugate transpose of a second vector and vice-versa, sums the results, and adds a matrix.

## Declaration

```swift
func cblas_chpr2(_ ORDER: CBLAS_ORDER, _ UPLO: CBLAS_UPLO, _ N: __LAPACK_int, _ ALPHA: OpaquePointer, _ X: OpaquePointer?, _ INCX: __LAPACK_int, _ Y: OpaquePointer?, _ INCY: __LAPACK_int, _ AP: OpaquePointer?)
```

## 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`: Order of matrix A and the number of elements in vectors x and y.
- `ALPHA`: Scaling factor that vector x is multiplied by.
- `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.
- `AP`: Matrix A in packed storage format. Overwritten by the results on return.

## Discussion

Discussion Calcuates alpha*x*conjg(y') + conjg(alpha)*y*conjg(x') + A, and stores the result in 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.

## See Also

### Single-precision complex matrix functions

- [cblas_caxpy(_:_:_:_:_:_:)](accelerate/cblas_caxpy(_:_:_:_:_:_:).md)
- [cblas_ccopy(_:_:_:_:_:)](accelerate/cblas_ccopy(_:_:_:_:_:).md)
- [cblas_cgbmv(_:_:_:_:_:_:_:_:_:_:_:_:_:_:)](accelerate/cblas_cgbmv(_:_:_:_:_:_:_:_:_:_:_:_:_:_:).md)
- [cblas_cgemm(_:_:_:_:_:_:_:_:_:_:_:_:_:_:)](accelerate/cblas_cgemm(_:_:_:_:_:_:_:_:_:_:_:_:_:_:).md)
- [cblas_cgemv(_:_:_:_:_:_:_:_:_:_:_:_:)](accelerate/cblas_cgemv(_:_:_:_:_:_:_:_:_:_:_:_:).md)
- [cblas_cgerc(_:_:_:_:_:_:_:_:_:_:)](accelerate/cblas_cgerc(_:_:_:_:_:_:_:_:_:_:).md)
- [cblas_cgeru(_:_:_:_:_:_:_:_:_:_:)](accelerate/cblas_cgeru(_:_:_:_:_:_:_:_:_:_:).md)
- [cblas_chbmv(_:_:_:_:_:_:_:_:_:_:_:_:)](accelerate/cblas_chbmv(_:_:_:_:_:_:_:_:_:_:_:_:).md)
- [cblas_chemm(_:_:_:_:_:_:_:_:_:_:_:_:_:)](accelerate/cblas_chemm(_:_:_:_:_:_:_:_:_:_:_:_:_:).md)
- [cblas_chemv(_:_:_:_:_:_:_:_:_:_:_:)](accelerate/cblas_chemv(_:_:_:_:_:_:_:_:_:_:_:).md)
- [cblas_cher(_:_:_:_:_:_:_:_:)](accelerate/cblas_cher(_:_:_:_:_:_:_:_:).md)
- [cblas_cher2(_:_:_:_:_:_:_:_:_:_:)](accelerate/cblas_cher2(_:_:_:_:_:_:_:_:_:_:).md)
- [cblas_cher2k(_:_:_:_:_:_:_:_:_:_:_:_:_:)](accelerate/cblas_cher2k(_:_:_:_:_:_:_:_:_:_:_:_:_:).md)
- [cblas_cherk(_:_:_:_:_:_:_:_:_:_:_:)](accelerate/cblas_cherk(_:_:_:_:_:_:_:_:_:_:_:).md)
- [cblas_chpmv(_:_:_:_:_:_:_:_:_:_:)](accelerate/cblas_chpmv(_:_:_:_:_:_:_:_:_:_:).md)