Calculate the nonnegative square root of a number
#include <math.h> double sqrt( double x ); float sqrtf( float x ); long double sqrtl( long double x );
These functions compute the nonnegative square root of x.
To check for error situations, use feclearexcept() and fetestexcept(). For example:
The nonnegative square root of the given number.
If x is: | These functions return: | Errors: |
---|---|---|
< -0.0, including -Inf | NaN | FE_INVALID |
±0.0 | x | — |
Inf | Inf | — |
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( "%f\n", sqrt(.5) ); except_flags = fetestexcept(FE_ALL_EXCEPT); if(except_flags) { /* An error occurred; handle it appropriately. */ } return EXIT_SUCCESS; }
produces the output:
0.707107
Safety: | |
---|---|
Cancellation point | No |
Interrupt handler | No |
Signal handler | No |
Thread | Yes |