NAG Library Routine Document

F16EHF (BLAS_DWAXPBY)

1  Purpose

2  Specification

3  Description

4  References

5  Parameters

1:     $\mathrm{N}$ – INTEGERInput

On entry: $n$, the number of elements in $x$, $y$ and $w$.

2:     $\mathrm{ALPHA}$ – REAL (KIND=nag_wp)Input

On entry: the scalar $\alpha$.

3:     $\mathrm{X}\left(1+\left(\mathbf{N}-1\right)\times \left|\mathbf{INCX}\right|\right)$ – REAL (KIND=nag_wp) arrayInput

On entry: the $n$-element vector $x$.

If $\mathbf{INCX}>0$, $x_{\mathit{i}}$ must be stored in $\mathbf{X}\left(\left(\mathit{i}-1\right)\times \left|\mathbf{INCX}\right|+1\right)$, for $\mathit{i}=1,2,\dots ,\mathbf{N}$.

If $\mathbf{INCX}<0$, $x_{\mathit{i}}$ must be stored in $\mathbf{X}\left(\left(\mathbf{N}-\mathit{i}\right)\times \left|\mathbf{INCX}\right|-1\right)$, for $\mathit{i}=1,2,\dots ,\mathbf{N}$.

Intermediate elements of X are not referenced.

4:     $\mathrm{INCX}$ – INTEGERInput

On entry: the increment in the subscripts of X between successive elements of $x$.

Constraint: $\mathbf{INCX}\ne 0$.

5:     $\mathrm{BETA}$ – REAL (KIND=nag_wp)Input

On entry: the scalar $\beta$.

6:     $\mathrm{Y}\left(1+\left(\mathbf{N}-1\right)\times \left|\mathbf{INCY}\right|\right)$ – REAL (KIND=nag_wp) arrayInput

On entry: the $n$-element vector $y$.

If $\mathbf{INCY}>0$, $y_{\mathit{i}}$ must be stored in $\mathbf{Y}\left(1+\left(\mathit{i}-1\right)\times \mathbf{INCY}\right)$, for $\mathit{i}=1,2,\dots ,\mathbf{N}$.

If $\mathbf{INCY}<0$, $y_{\mathit{i}}$ must be stored in $\mathbf{Y}\left(1-\left(\mathbf{N}-\mathit{i}\right)\times \mathbf{INCY}\right)$, for $\mathit{i}=1,2,\dots ,\mathbf{N}$.

Intermediate elements of Y are not referenced.

7:     $\mathrm{INCY}$ – INTEGERInput

On entry: the increment in the subscripts of Y between successive elements of $y$.

Constraint: $\mathbf{INCY}\ne 0$.

8:     $\mathrm{W}\left(1+\left(\mathbf{N}-1\right)\times \left|\mathbf{INCW}\right|\right)$ – REAL (KIND=nag_wp) arrayOutput

On exit: the $n$-element vector $w$.

If $\mathbf{INCW}>0$, $w_i$ is in $\mathbf{W}\left(1+\left(\mathit{i}-1\right)\times \mathbf{INCW}\right)$, for $\mathit{i}=1,2,\dots ,\mathbf{N}$.

If $\mathbf{INCW}<0$, $w_i$ is in $\mathbf{W}\left(1+\left(\mathbf{N}-\mathit{i}\right)\times \mathbf{INCW}\right)$, for $\mathit{i}=1,2,\dots ,\mathbf{N}$.

Intermediate elements of W are not referenced.

9:     $\mathrm{INCW}$ – INTEGERInput

On entry: the increment in the subscripts of W between successive elements of $w$.

Constraint: $\mathbf{INCW}\ne 0$.

6  Error Indicators and Warnings

7  Accuracy

8  Parallelism and Performance

9  Further Comments

10  Example

10.1  Program Text

Program Text (f16ehfe.f90)

10.2  Program Data

Program Data (f16ehfe.d)

10.3  Program Results

Program Results (f16ehfe.r)