From cppreference.com
Defined in header
floatsqrt(floatnum);doublesqrt(doublenum);longdoublesqrt(longdoublenum); (1)(until C++23)/*floating-point-type*/sqrt(/*floating-point-type*/num);(since C++23)
(constexpr since C++26)floatsqrtf(floatnum); (2)(since C++11)
(constexpr since C++26)longdoublesqrtl(longdoublenum); (3)(since C++11)
(constexpr since C++26)
(since C++26)
Defined in header
template</*math-floating-point*/V>constexpr/*deduced-simd-t*/<V>sqrt(constV&v_num); (S) (since C++26)
(since C++11)
Defined in header
template<classInteger>doublesqrt(Integernum); (A)(constexpr since C++26)1-3) Computes the square root of num. The library provides overloads of std::sqrt for all cv-unqualified floating-point types as the type of the parameter.(since C++23)
A) Additional overloads are provided for all integer types, which are treated as double.
(since C++11)Parameters
num - floating-point or integer value Return value
If no errors occur, square root of num (√num), 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
.
Domain error occurs if num is less than zero.
If the implementation supports IEEE floating-point arithmetic (IEC 60559),
If the argument is less than -0,
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 correctly rounded from the infinitely precise result. In particular, the exact result is produced if it can be represented in the floating-point type. The only other operations which require this are the
and the function
. Other functions, including
, are not so constrained.
The additional overloads are not required to be provided exactly as (A). They only need to be sufficient to ensure that for their argument num of integer type, std::sqrt(num) has the same effect as std::sqrt(static_cast<double>(num)).
Example
Run this code
#include<cerrno>#include<cfenv>#include<cmath>#include<cstring>#include<iostream>// #pragma STDC FENV_ACCESS ONintmain(){// normal usestd::cout<<"sqrt(100) = "<<std::sqrt(100)<<'\n'<<"sqrt(2) = "<<std::sqrt(2)<<'\n'<<"golden ratio = "<<(1+std::sqrt(5))/2<<'\n';// special valuesstd::cout<<"sqrt(-0) = "<<std::sqrt(-0.0)<<'\n';// error handlingerrno=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
(C++11)(C++11)
raises a number to the given power (xy)
(function)
(C++11)(C++11)(C++11)
computes cube root (3√x)
(function)
(C++11)(C++11)(C++11)
computes hypotenuse √x2
+y2
and √x2
+y2
+z2
(since C++17)
(function)
complex square root in the range of the right half-plane
(function template)
applies the function
to each element of valarray
(function template)
for sqrt