NAG FL Interface
f06etf (daxpyi)

1 Purpose

2 Specification

3 Description

4 References

5 Arguments

1: $\mathbf{nz}$ – Integer Input

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

2: $\mathbf{a}$ – Real (Kind=nag_wp) Input

On entry: the scalar $\alpha$.

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

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

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

4: $\mathbf{indx}\left(*\right)$ – Integer array Input

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

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.

5: $\mathbf{y}\left(*\right)$ – Real (Kind=nag_wp) array Input/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 elements corresponding to indices in indx are accessed.

On exit: the updated vector $y$.

6 Error Indicators and Warnings

7 Accuracy

8 Parallelism and Performance

9 Further Comments

10 Example