atan, atanl
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Header File
math.h
Category
Math Routines
Prototype
double atan(double x);
long double atanl(long double x);
Description
Calculates the arc tangent.
atan calculates the arc tangent of the input value.
atanl is the long double version; it takes a long double argument and returns a long double result.
Return Value
atan and atanl of a real argument return a value in the range -pi/2 to pi/2. Error handling for these functions can be modified through the functions _matherr and _matherrl.
Example
#include <stdio.h>
#include <math.h>
int main(void)
{
double result;
double x = 0.5;
result = atan(x);
printf("The arc tangent of %lf is %lf\n", x, result);
return(0);
}
Portability
POSIX | Win32 | ANSI C | ANSI C++ | |
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atan |
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atanl |
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