NAG Library Manual, Mark 28.5
```    Program f16eafe

!     F16EAF Example Program Text

!     Mark 28.5 Release. NAG Copyright 2022.

!     .. Use Statements ..
Use nag_library, Only: blas_ddot, nag_wp
!     .. Implicit None Statement ..
Implicit None
!     .. Parameters ..
Integer, Parameter               :: nin = 5, nout = 6
!     .. Local Scalars ..
Real (Kind=nag_wp)               :: alpha, beta, r
Integer                          :: conj, i, incx, incy, ix, iy, j, n
!     .. Local Arrays ..
Real (Kind=nag_wp), Allocatable  :: x(:), y(:)
!     .. Intrinsic Procedures ..
Intrinsic                        :: abs
!     .. Executable Statements ..
Write (nout,*) 'F16EAF Example Program Results'
Write (nout,*)

!     Skip heading in data file.

!     Accumulate two dot products, set beta=zero initially.
beta = 0.0_nag_wp

Do j = 1, 2
!       Read data for dot product.
Allocate (x(1+(n-1)*abs(incx)),y(1+(n-1)*abs(incy)))

!       Read the vectors x and y and store forwards or backwards
!       as determined by incx (resp. incy).
If (incx>0) Then
ix = 1
Else
ix = 1 - (n-1)*incx
End If

Do i = 1, n
ix = ix + incx
End Do

If (incy>0) Then
iy = 1
Else
iy = 1 - (n-1)*incy
End If

Do i = 1, n
iy = iy + incy
End Do

!       Compute r = beta*r + alpha*(x^T*y).
!       The NAG name equivalent of blas_ddot is f16eaf.
Call blas_ddot(conj,n,alpha,x,incx,beta,y,incy,r)

!       Reset beta for accumulation and deallocate x, y.
beta = 1.0_nag_wp
Deallocate (x,y)
End Do

Write (nout,99999) r

99999 Format (1X,'Accumulated dot product, r = ',F9.4)
End Program f16eafe
```