NAG Library Routine Document

f06exf (droti)

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Purpose

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Specification

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Description

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References

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Arguments

1:     $\mathbf{nz}$ – IntegerInput

On entry: the number of nonzeros in the sparse vector $x$.

2:     $\mathbf{x}\left(*\right)$ – Real (Kind=nag_wp) arrayInput/Output

Note: the dimension of the array x must be at least $\max \left(1,\mathbf{nz}\right)$.

On entry: the nonzero elements of the sparse vector $x$.

On exit: the transformed vector $x$.

3:     $\mathbf{indx}\left(*\right)$ – Integer arrayInput

Note: the dimension of the array indx must be at least $\max \left(1,\mathbf{nz}\right)$.

On entry: $\mathbf{indx}\left(\mathit{i}\right)$ must contain the index of $\mathbf{x}\left(\mathit{i}\right)$ in the sparse vector $x$, for $\mathit{i}=1,2,\dots ,\mathbf{nz}$.

Constraint: the indices must be distinct.

4:     $\mathbf{y}\left(*\right)$ – Real (Kind=nag_wp) arrayInput/Output

Note: the dimension of the array y must be at least ${\displaystyle \underset{\mathit{k}}{\max }}\left\{\mathbf{indx}\left(\mathit{k}\right)\right\}$.

On entry: the vector $y$. Only the elements corresponding to indices in indx are referenced.

On exit: the transformed vector $y$. Only elements corresponding to indices in indx are altered.

5:     $\mathbf{c}$ – Real (Kind=nag_wp)Input

On entry: the value $c$, the cosine of the rotation.

6:     $\mathbf{s}$ – Real (Kind=nag_wp)Input

On entry: the value $s$, the sine of the rotation.

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Error Indicators and Warnings

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Accuracy

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Parallelism and Performance

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Further Comments

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Example