Modern Math CArg

Home › Math Library › Math Library › CArg

CArg

Returns the phase angle of a complex number in radians, from -pi to pi.

Syntax

CArg( byref z as Complex ) as float64

Notes

• Principal value, on (-π, π]. atan2's convention, which is also C99's.
• The sign of a zero imaginary part decides the answer on the negative real axis: CArg( -1 + 0i ) is +π and CArg( -1 - 0i ) is -π. That is the branch cut, and it is visible only because the two zeros are distinguishable.
• AfxNova spelled this CArg, CArgument and CPhase.

Examples

#import "std/numeric"
using numeric

print CArg( CSet( 1, 0 ) )      '' 0
print CArg( CSet( 0, 1 ) )      '' 1.570796326794897   -- PI/2
print CArg( CSet( -1, 0.0 ) )   '' 3.141592653589793   -- above the cut
print CArg( CSet( -1, -0.0 ) )  '' -3.141592653589793   -- below it

---

Library: Math Library
Category: Math Library
Documented under: Members