?herk

Perform a rank-k update of the product of a complex matrix and a matrix. Matrix C is a complex Hermitian matrix.

That is, or .

alpha and beta are the real multiplication coefficients, and C is an n*n Hermitian matrix. In the first case, the matrix A is n*k, and in the second case, the matrix A is k*n.

Interface Definition

C interface:

void cblas_cherk(const enum CBLAS_ORDER Order, const enum CBLAS_UPLO Uplo, const enum CBLAS_TRANSPOSE Trans, const BLASINT N, const BLASINT K, const float alpha, const void *A, const BLASINT lda, const float beta, void *C, const BLASINT ldc);

void cblas_zherk(const enum CBLAS_ORDER Order, const enum CBLAS_UPLO Uplo, const enum CBLAS_TRANSPOSE Trans, const BLASINT N, const BLASINT K, const double alpha, const void *A, const BLASINT lda, const double beta, void *C, const BLASINT ldc);

Fortran interface:

CALL CHERK(UPLO, TRANS, N, K, ALPHA, A, LDA, BETA, C, LDC)

CALL ZHERK(UPLO, TRANS, N, K, ALPHA, A, LDA, BETA, C, LDC)

Parameters

Parameter	Type	Description	Input/Output
order	Enumeration type CBLAS_ORDER	Whether the matrix is in row- or column-major order.	Input
Uplo	Enumeration type CBLAS_UPLO	Indicates the storage mode of matrix C.	Input
Trans	Enumeration type CBLAS_TRANSPOSE	Whether matrix A is non-transposed or conjugated. If Trans = CblasNoTrans, If Trans = CblasConjTrans,	Input
N	Integer	Order of matrix C.	Input
K	Integer	Number of columns in matrix A when Trans = CblasNoTrans. Number of rows in matrix A when Trans = CblasConjTrans.	Input
alpha	Single-precision real type for cherk Double-precision real type for zherk	Multiplication coefficient.	Input
A	Single-precision complex type for cherk Double-precision complex type for zherk	Matrix A (lda, ka). If Trans = CblasNoTrans, ka = k; otherwise, ka = n.	Input
lda	Integer	If the matrix is column store and Trans = CblasNoTrans, lda must be at least max(1, n). Otherwise, lda must be at least max(1, k). If the matrix is row store and Trans = CblasNoTrans, lda must be at least max(1, k). Otherwise, lda must be at least max(1, n).	Input
beta	Single-precision real type for cherk Double-precision type for zherk	Multiplication coefficient.	Input
C	Single-precision complex type for cherk Double-precision complex type for zherk	Matrix C (ldc, n).	Input/Output
ldc	Integer	ldc must be at least max(1, n).	Input

Dependency

#include "kblas.h"

Examples

C interface:

      
       
         
         
               int n = 2, lda = 2, k = 2, ldc = 2; 
    float alpha = 2.0, beta = 2.0; 
    /** 
     *                    | 4.0 1.0   1.0 2.0 | 
     *     A(2 * 2)    =  | 3.0 2.0   4.0 1.0 | 
     *  
     *                    |  3.0 1.0  2.0  1.0 | 
     *     C(2 * 2)    =  | -1.0 1.0  -6.0 2.0 | 
     */ 
    float a[8] = {4.0, 1.0, 3.0, 2.0, 1.0, 2.0, 4.0, 1.0}; 
    float c[8] = {3.0, 1.0, -1.0, 1.0, 2.0, 1.0, -6.0, 2.0}; 
 
    cblas_cherk(CblasColMajor, CblasUpper, CblasConjTrans, n, k, alpha, a, lda, beta, c, ldc); 
    /** 
     * Output C 
     *                   | (66.0, 0.0)  (44.0, 6.0) | 
     *    C(2 * 2)    =  | (-1.0, 1.0)  (32.0, 0.0) | 
     * 
     */

          

        

      
     

Fortran interface:

      INTEGER :: N=2, K=2 
      INTEGER :: LDA=2, LDC=2 
      REAL(4) :: ALPHA=2.0 
      REAL(4) :: BETA=2.0 
      COMPLEX(4) :: A(2, 2), C(2, 2) 
      DATA A/(4.0, 1.0), (3.0, 2.0), (1.0, 2.0), (4.0, 1.0)/ 
      DATA B/(2.0, 1.0), (11.0, 2.0), (3.0, 2.0), (-2.0, 1.0)/ 
      DATA C/(3.0, 1.0), (-1.0, 1.0), (2.0, 1.0), (-6.0, 2.0)/ 
      EXTERNAL CHERK 
      CALL CHERK('U', 'C', N, K, ALPHA, A, LDA, BETA, C, LDC) 
 
*     Output C 
*                    | (66.0, 0.0)  (44.0, 6.0) | 
*     C(2 * 2)    =  | (-1.0, 1.0)  (32.0, 0.0) | 
*

Parent topic: KML_BLAS Level 3 Functions