Syntax
#include <math.h> double atan(double x); double atan2(double y, double x);Description
atan and atan2 calculate the arctangent of x and y/x, respectively.
atan returns a value in the range -pi/2 to pi/2 radians. atan2 returns a value in the range -pi to pi radians. If both arguments of atan2 are zero, the function sets errno to EDOM, and returns a value of 0.
This example calculates arctangents using the atan and atan2 functions.
#include <math.h>
int main(void)
{
double a,b,c,d;
c = 0.45;
d = 0.23;
a = atan(c);
b = atan2(c, d);
printf("atan( %lf ) = %lf\n", c, a);
printf("atan2( %lf, %lf ) = %lf\n", c, d, b);
return 0;
/****************************************************************************
The output should be:
atan( 0.450000 ) = 0.422854
atan2( 0.450000, 0.230000 ) = 1.098299
****************************************************************************/
}
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