NAG Library Routine Document

F06KCF

1  Purpose

2  Specification

3  Description

4  References

5  Parameters

1:     $\mathrm{N}$ – INTEGERInput

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

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

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

On entry: the vector $d$.

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

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

3:     $\mathrm{INCD}$ – INTEGERInput

On entry: the increment in the subscripts of D between successive elements of $d$.

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

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 array X must contain 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 $\mathit{i}=1,2,\dots ,\mathbf{N}$.

On exit: the updated vector $x$ stored in the array elements used to supply the original vector $x$.

Intermediate elements of X are unchanged.

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