NAG Library Routine Document

f06euf (dgthr)

1

Purpose

2

Specification

3

Description

4

References

5

Arguments

1:     $\mathbf{nz}$ – IntegerInput

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

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

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 elements corresponding to indices in indx are accessed.

3:     $\mathbf{x}\left(*\right)$ – Real (Kind=nag_wp) arrayOutput

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

On exit: the compressed vector $x$.

4:     $\mathbf{indx}\left(*\right)$ – 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 $\mathbf{y}\left(\mathit{i}\right)$, for $\mathit{i}=1,2,\dots ,\mathbf{nz}$, which is to be gathered into $x$.

6

Error Indicators and Warnings

7

Accuracy

8

Parallelism and Performance

9

Further Comments

10

Example