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Technical Reference: Base Operating System and Extensions, Volume 2
SAXPY, DAXPY, CAXPY, or ZAXPY Subroutine
Purpose
Computes a constant times a vector plus a vector.
Library
BLAS Library (libblas.a)
FORTRAN Syntax
SUBROUTINE SAXPY(N,A,X,INCX,Y,INCY)
INTEGER INCX, INCY, N
REAL A
REAL X(*), Y(*)
SUBROUTINE DAXPY(N,A,X,INCX,Y,INCY)
INTEGER INCX,INCY,N
DOUBLE PRECISION A
DOUBLE PRECISION X(*),Y(*)
SUBROUTINE CAXPY(N,A,X,INCX,Y,INCY)
INTEGER INCX,INCY,N
COMPLEX A
COMPLEX X(*),Y(*)
SUBROUTINE ZAXPY(N,A,X,INCX,Y,INCY)
INTEGER INCX,INCY,N
COMPLEX*16 A
COMPLEX*16 X(*),Y(*)
Description
The SAXPY, DAXPY, CAXPY, or ZAXPY subroutine computes a constant times a vector plus a vector:
Y = A * X + Y
Parameters
N |
On entry, N specifies the number of elements in X and Y; unchanged on exit. |
A |
On entry, A contains a constant to be multiplied by the X vector; unchanged on exit. |
X |
Vector of dimension at least (1 + (N-1) * abs(INCX) ); unchanged on exit. |
INCX |
On entry, INCX specifies the increment for the elements of X; unchanged on exit. |
Y |
Vector of dimension at least (1 + (N-1) * abs(INCY) ); the result is returned in vector Y. |
INCY |
On entry, INCY specifies the increment for the elements of Y; unchanged on exit. |
Error Codes
If SA = 0 or N <= 0, the subroutine returns immediately.
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