Atan calculates the arctangent of a double value; atan2 calculates the arctangent of the quotient of two doubles.

#include <math.h>

double atan (double x);

double atan2 (double x, double y);

Parameters

x

Any number(s) whose arctangent is calculated.

y

Any number(s) whose arctangent is calculated.

Remarks

atan2 uses the signs of both arguments to determine the quadrant of the return value.

Return Values

atan

Returns the arctangent result in the range -p/2 to p/2 radians.

atan2

Returns the arctangent result in the range -p to p radians.

Returns 0 if both arguments are 0, sets errno to EDOM and prints a DOMAIN error message to stderr.

Note:   This function does not return standard ANSI domain or range errors.

Requirements

See Also

acos, asin, cos, matherr, sin, tan