SSYMV/DSYMV/CHEMV/ZHEMV | Matrix-vector multiply |
Example 1 Form the REAL*4 matrix-vector product y = Ax, where A is a 9-by-9 real symmetric matrix whose upper triangle is stored in the upper triangle of an array A whose dimensions are 10-by-10, x is a real vector 9 elements long stored in an array X of dimension 10, and y is a real vector 9 elements long stored in an array Y, also of dimension 10.
CHARACTER*1 UPLO | |
INTEGER*4 | N,LDA,INCX,INCY | |
REAL*4 | ALPHA,BETA,A(10,10),X(10),Y(10) |
UPLO = ’U’ | | |
N = 9 | | |
ALPHA = 1.0 | | |
BETA = 0.0 | | |
LDA = 10 | | |
INCX = 1 | | |
INCY = 1 | | |
CALL SSYMV (UPLO,N,ALPHA,A,LDA,X,INCX,BETA,Y,INCY) |
Example 2 Form the COMPLEX*8 matrix-vector product y = | 1 |
--y – ρAx , where ρ is a |
| | 2 |
complex scalar, A is a 9-by-9 complex Hermitian matrix whose lower triangle is stored in the lower triangle of an array A whose dimensions are 10-by-10, x is a complex vector 9 elements long stored in an array X of dimension 10, and y is a complex vector 9 elements long stored in an array Y, also of dimension 10.
INTEGER*4 N,LDA
COMPLEX*8 RHO,A(10,10),X(10),Y(10)
N = 9
LDA = 10
CALL CHEMV (’LOWER’,N,-RHO,A,LDA,X,1,(0.5,0.0),Y,1)