atan(), atanf()

Compute the arctangent of an angle

Synopsis:

#include <math.h>

double atan( double x );

float atanf( float x );

Arguments:

x

The tangent for which you want to find the angle.

Library:

libm

Use the -l m option to qcc to link against this library.

Description:

These functions compute the arctangent (specified in radians) of x.

Returns:

The arctangent, in the range (-π/2, π/2).

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If an error occurs, these functions return 0, but this is also a valid mathematical result. If you want to check for errors, set errno to 0, call the function, and then check errno again. These functions don't change errno if no errors occurred.

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Examples:

#include <stdio.h>
#include <math.h>
#include <stdlib.h>

int main( void )
{
    printf( "%f\n", atan(.5) );
    return EXIT_SUCCESS;
}

produces the output:

0.463648

Classification:

ANSI, POSIX 1003.1

See also:

acos(), asin(), atan2()