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atan2 functions


[Syntax]

double atan2(double y, double x)

float atan2f(float y, float x)

long double atan2l(long double y, long double x) [V2.01.00 or later]

[Description]

These functions calculate the arc tangent of y/x.

 

[Special case]

Condition

Return value

Exception

x==0, y==0

NaN

EDOM

x==±∞, y==±∞

NaN

EDOM

Underflow occurred

±0

ERANGE

x<0, y==0

π

-

x==0

±π/2

-