different from its earlier incarnation as it appears in [1]_, in that the call to `elliprc` (or ``atan``/``atanh``, see [4]_) is no longer needed in the inner loop. Asymptotic approximations are used where arguments differ widely in the order of magnitude. [5]_ The input values are subject to certain sufficient but not necessary constraints when input arguments are complex. Notably, ``x``, ``y``, and ``z`` must have non-negative real parts, unless two of them are non-negative and complex-conjugates to each other while the other is a real non-negative number. [1]_ If the inputs do not satisfy the sufficient condition described in Ref. [1]_ they are rejected outright with the output set to NaN. In the case where one of ``x``, ``y``, and ``z`` is equal to ``p``, the function ``elliprd`` should be preferred because of its less restrictive domain. .. versionadded:: 1.8.0 References ---------- .. [1] B. C. Carlson, "Numerical computation of real or complex elliptic integrals," Numer. Algorithm, vol. 10, no. 1, pp. 13-26, 1995. https://arxiv.org/abs/math/9409227 https://doi.org/10.1007/BF02198293 .. [2] B. C. Carlson, ed., Chapter 19 in "Digital Library of Mathematical Functions," NIST, US Dept. of Commerce. https://dlmf.nist.gov/19.20.iii .. [3] B. C. Carlson, J. FitzSimmons, "Reduction Theorems for Elliptic Integrands with the Square Root of Two Quadratic Factors," J. Comput. Appl. Math., vol. 118, nos. 1-2, pp. 71-85, 2000. https://doi.org/10.1016/S0377-0427(00)00282-X .. [4] F. Johansson, "Numerical Evaluation of Elliptic Functions, Elliptic Integrals and Modular Forms," in J. Blumlein, C. Schneider, P. Paule, eds., "Elliptic Integrals, Elliptic Functions and Modular Forms in Quantum Field Theory," pp. 269-293, 2019 (Cham, Switzerland: Springer Nature Switzerland) https://arxiv.org/abs/1806.06725 https://doi.org/10.1007/978-3-030-04480-0 .. [5] B. C. Carlson, J. L. Gustafson, "Asymptotic Approximations for Symmetric Elliptic Integrals," SIAM J. Math. Anls., vol. 25, no. 2, pp. 288-303, 1994. https://arxiv.org/abs/math/9310223 https://doi.org/10.1137/S0036141092228477 Examples -------- Basic homogeneity property: >>> import numpy as np >>> from scipy.special import elliprj >>> x = 1.2 + 3.4j >>> y = 5. >>> z = 6. >>> p = 7. >>> scale = 0.3 - 0.4j >>> elliprj(scale*x, scale*y, scale*z, scale*p) (0.10834905565679157+0.19694950747103812j) >>> elliprj(x, y, z, p)*np.power(scale, -1.5) (0.10834905565679556+0.19694950747103854j) Reduction to simpler elliptic integral: >>> elliprj(x, y, z, z) (0.08288462362195129-0.028376809745123258j) >>> from scipy.special import elliprd >>> elliprd(x, y, z) (0.08288462362195136-0.028376809745123296j) All arguments coincide: >>> elliprj(x, x, x, x) (-0.03986825876151896-0.14051741840449586j) >>> np.power(x, -1.5) (-0.03986825876151894-0.14051741840449583j) Ú