std::sqrt,std::sqrtf,std::sqrtl(3)

NAME
std::sqrt,std::sqrtf,std::sqrtl - std::sqrt,std::sqrtf,std::sqrtl

Synopsis
   Defined in header <cmath>
   float sqrt ( float arg );
   float sqrtf( float arg ); (since C++11)
   double sqrt ( double arg ); (1) (2)
   long double sqrt ( long double arg );
   long double sqrtl( long double arg ); (3) (since C++11)
   double sqrt ( IntegralType arg ); (4) (since C++11)
   1-3) Computes the square root of arg.
   4) A set of overloads or a function template accepting an argument of any integral
   type. Equivalent to (2) (the argument is cast to double).

Parameters
   arg - Value of a floating-point or integral type

Return value
   If no errors occur, square root of arg (\({\small \sqrt{arg} }\)
   √
   arg), is returned.
   If a domain error occurs, an implementation-defined value is returned (NaN where
   supported)
   If a range error occurs due to underflow, the correct result (after rounding) is
   returned.

Error handling
   Errors are reported as specified in math_errhandling
   Domain error occurs if arg is less than zero.
   If the implementation supports IEEE floating-point arithmetic (IEC 60559),
     * If the argument is less than -0, FE_INVALID is raised and NaN is returned.
     * If the argument is +∞ or ±0, it is returned, unmodified.
     * If the argument is NaN, NaN is returned

Notes
   std::sqrt is required by the IEEE standard to be exact. The only other operations
   required to be exact are the arithmetic operators and the function std::fma. After
   rounding to the return type (using default rounding mode), the result of std::sqrt
   is indistinguishable from the infinitely precise result. In other words, the error
   is less than 0.5 ulp. Other functions, including std::pow, are not so constrained.

Example
// Run this code
 #include <iostream>
 #include <cmath>
 #include <cerrno>
 #include <cfenv>
 #include <cstring>
 #pragma STDC FENV_ACCESS ON
 int main()
 {
     // normal use
     std::cout << "sqrt(100) = " << std::sqrt(100) << '\n'
               << "sqrt(2) = " << std::sqrt(2) << '\n'
               << "golden ratio = " << (1+std::sqrt(5))/2 << '\n';
     // special values
     std::cout << "sqrt(-0) = " << std::sqrt(-0.0) << '\n';
     // error handling
     errno = 0;
     std::feclearexcept(FE_ALL_EXCEPT);
     std::cout << "sqrt(-1.0) = " << std::sqrt(-1) << '\n';
     if(errno == EDOM)
         std::cout << " errno = EDOM " << std::strerror(errno) << '\n';
     if(std::fetestexcept(FE_INVALID))
         std::cout << " FE_INVALID raised\n";
 }

Possible output:
 sqrt(100) = 10
 sqrt(2) = 1.41421
 golden ratio = 1.61803
 sqrt(-0) = -0
 sqrt(-1.0) = -nan
     errno = EDOM Numerical argument out of domain
     FE_INVALID raised

See also
   pow
   powf raises a number to the given power (\(\small{x^y}\)x^y)
   powl (function)
   (C++11)
   (C++11)
   cbrt computes cubic root (\(\small{\sqrt[3]{x} }\)
   cbrtf 3
   cbrtl √
   (C++11) x)
   (C++11) (function)
   (C++11)
                       computes square root of the sum of the squares of two or three
                       (C++17) given numbers (\(\scriptsize{\sqrt{x^2+y^2} }\)
                       √
   hypot x2
   hypotf +y2
   hypotl ), (\(\scriptsize{\sqrt{x^2+y^2+z^2} }\)
   (C++11) √
   (C++11) x2
   (C++11) +y2
                       +z2
                       )
                       (function)
   sqrt(std::complex) complex square root in the range of the right half-plane
                       (function template)
   sqrt(std::valarray) applies the function std::sqrt to each element of valarray
                       (function template)