Compute the arccosine of an angle
#include <math.h> double acos( double x ); float acosf( float x ); long double acosl( long double x );
Your system requirements will determine how you should work with these libraries:
These functions compute the arccosine (in radians) of x.
To check for error situations, use feclearexcept() and fetestexcept(). For example:
The arccosine in the range [0.0, π].
If x is: | These functions return: | Errors: |
---|---|---|
Finite, but not in the range [-1,1] | NaN | FE_INVALID |
±Inf | NaN | FE_INVALID |
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 <fenv.h> #include <stdlib.h> int main( void ) { int except_flags; feclearexcept(FE_ALL_EXCEPT); printf( "acos(0.5) is %f\n", acos(0.5) ); except_flags = fetestexcept(FE_ALL_EXCEPT); if(except_flags) { /* An error occurred; handle it appropriately. */ } return EXIT_SUCCESS; }
produces the output:
1.047197
Safety: | |
---|---|
Cancellation point | No |
Interrupt handler | Yes |
Signal handler | Yes |
Thread | Yes |