std::comp_ellint_1, std::comp_ellint_1f, std::comp_ellint_1l
double comp_ellint_1( float arg );
double comp_ellint_1( long double arg );
float comp_ellint_1f( float arg );
As all special functions, comp_ellint_1 is only guaranteed to be available in <cmath> if __STDCPP_MATH_SPEC_FUNCS__ is defined by the implementation to a value at least 201003L and if the user defines __STDCPP_WANT_MATH_SPEC_FUNCS__ before including any standard library headers.
[edit] Parameters
[edit] Return value
If no errors occur, value of the complete elliptic integral of the first kind of arg, that is ellint_1(arg, π/2), is returned.
[edit] Error handling
Errors may be reported as specified in math_errhandling.
- If the argument is NaN, NaN is returned and domain error is not reported.
- If |arg| > 1, a domain error may occur.
[edit] Notes
Implementations that do not support TR 29124 but support TR 19768, provide this function in the header tr1/cmath and namespace std::tr1.
An implementation of this function is also available in boost.math.
[edit] Example
(works as shown with gcc 6.0)
#define __STDCPP_WANT_MATH_SPEC_FUNCS__ 1 #include <cmath> #include <iostream> int main() { double hpi = std::acos (-1) / 2; std::cout << "K(0) = " << std::comp_ellint_1 (0) << '\n' << "π/2 = " << hpi << '\n' << "K(0.5) = " << std::comp_ellint_1 (0.5) << '\n' << "F(0.5, π/2) = " << std::ellint_1 (0.5, hpi) << '\n'; }
Output:
K(0) = 1.5708 π/2 = 1.5708 K(0.5) = 1.68575 F(0.5, π/2) = 1.68575
[edit] External links
Weisstein, Eric W. "Complete Elliptic Integral of the First Kind." From MathWorld--A Wolfram Web Resource.