29 Numerics library [numerics]

29.9 Mathematical functions for floating-point types [c.math]

29.9.5 Mathematical special functions [sf.cmath]

29.9.5.11 Incomplete elliptic integral of the first kind [sf.cmath.ellint_1]

double ellint_1(double k, double phi); float ellint_1f(float k, float phi); long double ellint_1l(long double k, long double phi);

Effects: These functions compute the incomplete elliptic integral of the first kind of their respective arguments k and phi (phi measured in radians).

Returns:

F(k,ϕ)=ϕ0dθ1k2sin2θ,for |k|1

where k is k and φ is phi.