maxframe.tensor.special.elliprf#

maxframe.tensor.special.elliprf(x, y, z, **kwargs)[source]#

Completely-symmetric elliptic integral of the first kind.

The function RF is defined as [1]

\[R_{\mathrm{F}}(x, y, z) = \frac{1}{2} \int_0^{+\infty} [(t + x) (t + y) (t + z)]^{-1/2} dt\]
Parameters:

  • x (array_like) – Real or complex input parameters. x, y, or z can be any number in the complex plane cut along the negative real axis, but at most one of them can be zero.

  • y (array_like) – Real or complex input parameters. x, y, or z can be any number in the complex plane cut along the negative real axis, but at most one of them can be zero.

  • z (array_like) – Real or complex input parameters. x, y, or z can be any number in the complex plane cut along the negative real axis, but at most one of them can be zero.

  • out (ndarray, optional) – Optional output array for the function values

Returns:

R – Value of the integral. If all of x, y, and z are real, the return value is real. Otherwise, the return value is complex.

Return type:

scalar or ndarray

See also

elliprc

Degenerate symmetric integral.

elliprd

Symmetric elliptic integral of the second kind.

elliprg

Completely-symmetric elliptic integral of the second kind.

elliprj

Symmetric elliptic integral of the third kind.

Notes

The code implements Carlson’s algorithm based on the duplication theorems and series expansion up to the 7th order (cf.: https://dlmf.nist.gov/19.36.i) and the AGM algorithm for the complete integral. [2]

References