NAG Library Routine Document

is calculated using Smith's algorithm with scaling, from Li et al. (2002), which ensures that no unnecessary overflow or underflow occurs at intermediate stages of the computation.

4

References

Li X S, Demmel J W, Bailey D H, Henry G, Hida Y, Iskandar J, Kahan W, Kapur A, Martin M C, Tung T and Yoo D J (2002) Design, implementation and testing of extended and mixed precision BLAS ACM Trans. Math. Soft. 28(2) 152–205

5

Arguments

1: $xr$ – Real (Kind=nag_wp)Input
2: $xi$ – Real (Kind=nag_wp)Input: On entry: $x_{r}$ and $x_{i}$ , the real and imaginary parts of $x$ , respectively.
3: $yr$ – Real (Kind=nag_wp)Input
4: $yi$ – Real (Kind=nag_wp)Input: On entry: $y_{r}$ and $y_{i}$ , the real and imaginary parts of $y$ , respectively.
5: $zr$ – Real (Kind=nag_wp)Output
6: $zi$ – Real (Kind=nag_wp)Output: On exit: $z_{r}$ and $z_{i}$ , the real and imaginary parts of $z$ , respectively.

6

Error Indicators and Warnings

None.

7

Accuracy

The result should be correct to machine precision.

8

Parallelism and Performance

a02acf is not threaded in any implementation.

9

Further Comments

The time taken by a02acf is negligible.

This routine must not be called with

yr = 0.0

and

yi = 0.0

10

Example

This example finds the value of

(- 1.7 + 2.6 i) / (- 3.1 - 0.9 i)

NAG Library Routine Document

a02acf (divide)

▸▿ Contents

1 Purpose

2 Specification

3 Description

4 References

5 Arguments

6 Error Indicators and Warnings

7 Accuracy

8 Parallelism and Performance

9 Further Comments

10 Example

10.1 Program Text

10.2 Program Data

10.3 Program Results

1

Purpose

2

Specification

3

Description