NAG Library Routine Document

F06FUF

1  Purpose

2  Specification

3  Description

4  References

5  Parameters

1:     N – INTEGERInput

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

2:     Z($*$) – REAL (KIND=nag_wp) arrayInput

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

On entry: the vector $z$, as returned by F06FSF.

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

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

3:     INCZ – INTEGERInput

On entry: the increment in the subscripts of Z between successive elements of $z$.

4:     Z1 – REAL (KIND=nag_wp)Input

On entry: the scalar $\zeta$, as returned by F06FSF.

If $\zeta =0$, $P$ is assumed to be the unit matrix and the transformation is skipped.

5:     ALPHA – REAL (KIND=nag_wp)Input/Output

On entry: the original scalar $\alpha$.

On exit: the transformed scalar $\alpha$.

6:     X($*$) – REAL (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 original 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 transformed vector $x$ stored in the same array elements used to supply the original vector $x$.

7:     INCX – INTEGERInput

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

6  Error Indicators and Warnings

7  Accuracy

8  Further Comments

9  Example