ellippy.carlson.elliprg#
- ellippy.carlson.elliprg(x, y, z)[source]#
Computes Carlson symmetric integral RG.
\[R_G(x,y,z) = \frac{1}{4}\int_{0}^{\infty}\frac{t} {\sqrt{(t+x)(t+y)(t+z)}}\,\left(\dfrac{x}{t+x}+\dfrac{y}{t+y}+\dfrac{z}{t+z}\right)\,\mathrm{d}t\]- Parameters:
x (
ArrayLike) – Real-valued parameter.y (
ArrayLike) – Real-valued parameter.z (
ArrayLike) – Real-valued parameter.
- Returns:
Scalar or numpy.ndarray broadcast from inputs.
- Raises:
ValueError – If any of x, y, or z is negative or infinite, or inputs contain NaN.
Graph
Special Cases
RG(x, x, x) = sqrt(x)
RG(0, y, y) = π/4 * sqrt(y)
RG(x, y, y) = (y * RC(x, y) + sqrt(x))/2
RG(0, 0, z) = sqrt(z)/2
Related Functions
- With c = csc²φ, r = 1/x², and kc² = 1 - m,
E(m) = 2·RG(0, kc², 1)
5(φ, m) = 2·RG(c - 1, c - m, c) - (c - 1)·RF(c - 1, c - m, c) - sqrt((c - 1) * (c - m) / c)
Notes
The parameters x, y, and z are symmetric. This means swapping them does not change the value of the function. At most one of them can be zero.
References
Maddock, John, Paul Bristow, Hubert Holin, and Xiaogang Zhang. “Boost Math Library: Special Functions - Elliptic Integrals.” Accessed April 17, 2025. https://www.boost.org/doc/libs/1_88_0/libs/math/doc/html/math_toolkit/ellint.html.
Carlson, B. C. “DLMF: Chapter 19 Elliptic Integrals.” Accessed February 19, 2025. https://dlmf.nist.gov/19.
Pornsiriprasert, Sira. Ellip: Elliptic Integrals for Rust. V. 0.5.1. Released October 10, 2025. https://docs.rs/ellip/0.5.1/ellip/index.html.