NAG Library Routine Document

F06FKF

1  Purpose

2  Specification

3  Description

4  References

5  Parameters

1:     $\mathrm{N}$ – INTEGERInput

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

2:     $\mathrm{W}\left(*\right)$ – REAL (KIND=nag_wp) arrayInput

Note: the dimension of the array W must be at least $\max \left(1,1+\left(\mathbf{N}-1\right)\times \left|\mathbf{INCW}\right|\right)$.

On entry: $w$, the vector of weights.

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

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

Constraint: All weights must be non-negative.

3:     $\mathrm{INCW}$ – INTEGERInput

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

4:     $\mathrm{X}\left(*\right)$ – REAL (KIND=nag_wp) arrayInput

Note: the dimension of the array X must be at least $\max \left(1,1+\left(\mathbf{N}-1\right)\times \left|\mathbf{INCX}\right|\right)$.

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

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

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

Intermediate elements of X are not referenced.

5:     $\mathrm{INCX}$ – INTEGERInput

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

6  Error Indicators and Warnings

7  Accuracy

8  Parallelism and Performance

9  Further Comments

10  Example