Updated: April 19, 2023 |
Compute the arctangent of an angle
#include <math.h> double atan( double x ); float atanf( float x ); long double atanl( long double x );
Your system requirements will determine how you should work with these libraries:
These functions compute the arctangent (in radians) of x.
To check for error situations, use feclearexcept() and fetestexcept(). For example:
The arctangent, in the range [-π/2, π/2].
If x is: | These functions return: | Errors: |
---|---|---|
±0.0 | x | — |
Inf | π/2 | — |
-Inf | -π/2 | — |
NaN | NaN | — |
These functions raise FE_INEXACT if the FPU reports that the result can't be exactly represented as a floating-point number.
#include <stdio.h> #include <math.h> #include <stdlib.h> #include <fenv.h> int main( void ) { int except_flags; feclearexcept(FE_ALL_EXCEPT); printf( "%f\n", atan(.5) ); except_flags = fetestexcept(FE_ALL_EXCEPT); if(except_flags) { /* An error occurred; handle it appropriately. */ } return EXIT_SUCCESS; }
produces the output:
0.463648
Safety: | |
---|---|
Cancellation point | No |
Interrupt handler | Yes |
Signal handler | Yes |
Thread | Yes |