NAG Library Routine Document

F06CCF

+− Contents

1 Purpose

9 Example

F06CCF reconstructs the parameters

c

(real) and

s

(complex) of a complex plane rotation from the tangent of that rotation.

SUBROUTINE F06CCF (

T, C, S)

REAL (KIND=nag_wp)	C
COMPLEX (KIND=nag_wp)	T, S

F06CCF reconstructs the parameters

c

(real) and

s

(complex) of a complex plane rotation, from the value of the tangent

t

, as returned by F06CAF:

c = \frac{1}{\sqrt{1 + {|t|}^{2}}}, s = c t,

so that

c

is always real and non-negative.

|t| < \sqrt{ε}

, where

ε

is the machine precision, the routine sets

c = 1

and

s = t

None.

1: T – COMPLEX (KIND=nag_wp)Input: On entry: the value $t$ , the tangent of the rotation.
2: C – REAL (KIND=nag_wp)Output: On exit: the value $c$ , the cosine of the rotation.
3: S – COMPLEX (KIND=nag_wp)Output: On exit: the value $s$ , the sine of the rotation.