29 Numerics library [numerics]

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

29.9.5 Mathematical special functions [sf.cmath]

29.9.5.13 Incomplete elliptic integral of the third kind [sf.cmath.ellint_3]

double       ellint_3(double k, double nu, double phi);
float        ellint_3f(float k, float nu, float phi);
long double  ellint_3l(long double k, long double nu, long double phi);

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

Returns:

$Π (ν, k, ϕ) = \int_{0}^{ϕ} \frac{d θ}{(1 - ν sin^{2} θ) \sqrt{1 - k^{2} sin^{2} θ}}, for | k | \leq 1$

where ν is nu, k is k, and φ is phi.