?her2
Perform a rank-2 update of a complex Hermitian matrix.
That is, 
. A is an n*n Hermitian matrix, alpha is a multiplication coefficient, and x and y are vectors including n elements each.
Interface Definition
C interface:
void cblas_cher2(const enum CBLAS_ORDER order, const enum CBLAS_UPLO Uplo, const BLASINT N, const void *alpha, const void *X, const BLASINT incX, const void *Y, const BLASINT incY, void *A, const BLASINT lda);
void cblas_zher2(const enum CBLAS_ORDER order, const enum CBLAS_UPLO Uplo, const BLASINT N, const void *alpha, const void *X, const BLASINT incX, const void *Y, const BLASINT incY, void *A, const BLASINT lda);
Fortran interface:
CALL CHER2(UPLO, N, ALPHA, X, INCX, Y, INCY, A, LDA)
CALL ZHER2(UPLO, N, ALPHA, X, INCX, Y, INCY, A, LDA)
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 the Hermitian matrix (upper triangle or lower triangle).
|
Input |
N |
Integer |
Number of elements in vector X. |
Input |
alpha |
|
Multiplication coefficient. |
Input |
X |
|
Matrix X. The length must be at least 1+(n-1)*abs(incX). |
Input |
incX |
Integer |
Increment for elements in vector X. The value cannot be 0. |
Input |
Y |
|
Matrix Y. The length must be at least 1+(n-1)*abs(incY). |
Input |
incY |
Integer |
Increment for elements in vector Y. The value cannot be 0. |
Input |
A |
|
Matrix A (lda, n). |
Output |
lda |
Integer |
Length of the main dimension of matrix A. The value of lda must be greater than or equal to max(1, n). |
Input |
Dependency
#include "kblas.h"
Examples
C interface:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 | int n = 3; float alpha[2] = {1.0, 2.9}; int incx = 1, incy = 1; /** * | (1.0, 0.0) (13.0, 5.0) (12.0, 0) | * A = | (13.0, -5.0) (2.0, 0.0) (4.0, -18.0) | * | (12.0, 0) (4.0, 18.0) (3.0, 0.0) | */ float ap[18] = {1.0, 0, 13.0, -5.0, 12.0, 0, 13.0, 5.0, 2.0, 0, 4.0, 18.0, 12.0, 0, 4.0, -18.0, 3.0, 0}; float x[6] = {2.0, -2.0, 14.0, 1, 3.0, 4.0}; float y[6] = {2.0, -2.0, 14.0, 1, 3.0, 4.0}; cblas_cher2(CblasColMajor, CblasLower, n, alpha, x, incx, y, incy, ap, 3); /** * | 17.000000 0.000000 13.000000 5.000000 12.000000 0.000000 | * Output A = | 65.000000 55.000000 396.000000 0.000000 4.000000 -18.000000| * | 8.000000 28.000000 96.000000 124.000000 53.000000 0.000000 | */ |
Fortran interface:
INTEGER :: N=3
COMPLEX(4) :: ALPHA=(1.0, 2.9)
INTEGER :: INCX=1
INTEGER :: INCY=1
COMPLEX(4) :: AP(3, 3)
DATA AP/(1.0, 0), (13.0, -5.0), (12.0, 0), (13.0, 5.0), (2.0, 0),
$ (4.0, 18.0), (12.0, 0), (4.0, -18.0), (3.0, 0)/
COMPLEX(4) :: X(3)
DATA X/(2.0, -2.0), (14.0, 1), (3.0, 4.0)/
COMPLEX(4) :: Y(3)
DATA Y/(2.0, -2.0), (14.0, 1), (3.0, 4.0)/
EXTERNAL CHER2
CALL CHER2('L', N, ALPHA, X, INCX, Y, INCY, A, LDA)
* | 17.000000 0.000000 13.000000 5.000000 12.000000 0.000000 |
* Output A = | 65.000000 55.000000 396.000000 0.000000 4.000000 -18.000000|
* | 8.000000 28.000000 96.000000 124.000000 53.000000 0.000000 |