// Special functions -*- C++ -*- // Copyright (C) 2006-2020 Free Software Foundation, Inc. // // This file is part of the GNU ISO C++ Library. This library is free // software; you can redistribute it and/or modify it under the // terms of the GNU General Public License as published by the // Free Software Foundation; either version 3, or (at your option) // any later version. // // This library is distributed in the hope that it will be useful, // but WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the // GNU General Public License for more details. // // Under Section 7 of GPL version 3, you are granted additional // permissions described in the GCC Runtime Library Exception, version // 3.1, as published by the Free Software Foundation. // You should have received a copy of the GNU General Public License and // a copy of the GCC Runtime Library Exception along with this program; // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see // <http://www.gnu.org/licenses/>. /** @file tr1/ell_integral.tcc * This is an internal header file, included by other library headers. * Do not attempt to use it directly. @headername{tr1/cmath} */ // // ISO C++ 14882 TR1: 5.2 Special functions // // Written by Edward Smith-Rowland based on: // (1) B. C. Carlson Numer. Math. 33, 1 (1979) // (2) B. C. Carlson, Special Functions of Applied Mathematics (1977) // (3) The Gnu Scientific Library, http://www.gnu.org/software/gsl // (4) Numerical Recipes in C, 2nd ed, by W. H. Press, S. A. Teukolsky, // W. T. Vetterling, B. P. Flannery, Cambridge University Press // (1992), pp. 261-269 #ifndef _GLIBCXX_TR1_ELL_INTEGRAL_TCC #define _GLIBCXX_TR1_ELL_INTEGRAL_TCC 1 namespace std _GLIBCXX_VISIBILITY(default) { _GLIBCXX_BEGIN_NAMESPACE_VERSION #if _GLIBCXX_USE_STD_SPEC_FUNCS #elif defined(_GLIBCXX_TR1_CMATH) namespace tr1 { #else # error do not include this header directly, use <cmath> or <tr1/cmath> #endif // [5.2] Special functions // Implementation-space details. namespace __detail { /** * @brief Return the Carlson elliptic function @f$ R_F(x,y,z) @f$ * of the first kind. * * The Carlson elliptic function of the first kind is defined by: * @f[ * R_F(x,y,z) = \frac{1}{2} \int_0^\infty * \frac{dt}{(t + x)^{1/2}(t + y)^{1/2}(t + z)^{1/2}} * @f] * * @param __x The first of three symmetric arguments. * @param __y The second of three symmetric arguments. * @param __z The third of three symmetric arguments. * @return The Carlson elliptic function of the first kind. */ template<typename _Tp> _Tp __ellint_rf(_Tp __x, _Tp __y, _Tp __z) { const _Tp __min = std::numeric_limits<_Tp>::min(); const _Tp __max = std::numeric_limits<_Tp>::max(); const _Tp __lolim = _Tp(5) * __min; const _Tp __uplim = __max / _Tp(5); if (__x < _Tp(0) || __y < _Tp(0) || __z < _Tp(0)) std::__throw_domain_error(__N("Argument less than zero " "in __ellint_rf.")); else if (__x + __y < __lolim || __x + __z < __lolim || __y + __z < __lolim) std::__throw_domain_error(__N("Argument too small in __ellint_rf")); else { const _Tp __c0 = _Tp(1) / _Tp(4); const _Tp __c1 = _Tp(1) / _Tp(24); const _Tp __c2 = _Tp(1) / _Tp(10); const _Tp __c3 = _Tp(3) / _Tp(44); const _Tp __c4 = _Tp(1) / _Tp(14); _Tp __xn = __x; _Tp __yn = __y; _Tp __zn = __z; const _Tp __eps = std::numeric_limits<_Tp>::epsilon(); const _Tp __errtol = std::pow(__eps, _Tp(1) / _Tp(6)); _Tp __mu; _Tp __xndev, __yndev, __zndev; const unsigned int __max_iter = 100; for (unsigned int __iter = 0; __iter < __max_iter; ++__iter) { __mu = (__xn + __yn + __zn) / _Tp(3); __xndev = 2 - (__mu + __xn) / __mu; __yndev = 2 - (__mu + __yn) / __mu; __zndev = 2 - (__mu + __zn) / __mu; _Tp __epsilon = std::max(std::abs(__xndev), std::abs(__yndev)); __epsilon = std::max(__epsilon, std::abs(__zndev)); if (__epsilon < __errtol) break; const _Tp __xnroot = std::sqrt(__xn); const _Tp __ynroot = std::sqrt(__yn); const _Tp __znroot = std::sqrt(__zn); const _Tp __lambda = __xnroot * (__ynroot + __znroot) + __ynroot * __znroot; __xn = __c0 * (__xn + __lambda); __yn = __c0 * (__yn + __lambda); __zn = __c0 * (__zn + __lambda); } const _Tp __e2 = __xndev * __yndev - __zndev * __zndev; const _Tp __e3 = __xndev * __yndev * __zndev; const _Tp __s = _Tp(1) + (__c1 * __e2 - __c2 - __c3 * __e3) * __e2 + __c4 * __e3; return __s / std::sqrt(__mu); } } /** * @brief Return the complete elliptic integral of the first kind * @f$ K(k) @f$ by series expansion. * * The complete elliptic integral of the first kind is defined as * @f[ * K(k) = F(k,\pi/2) = \int_0^{\pi/2}\frac{d\theta} * {\sqrt{1 - k^2sin^2\theta}} * @f] * * This routine is not bad as long as |k| is somewhat smaller than 1 * but is not is good as the Carlson elliptic integral formulation. * * @param __k The argument of the complete elliptic function. * @return The complete elliptic function of the first kind. */ template<typename _Tp> _Tp __comp_ellint_1_series(_Tp __k) { const _Tp __kk = __k * __k; _Tp __term = __kk / _Tp(4); _Tp __sum = _Tp(1) + __term; const unsigned int __max_iter = 1000; for (unsigned int __i = 2; __i < __max_iter; ++__i) { __term *= (2 * __i - 1) * __kk / (2 * __i); if (__term < std::numeric_limits<_Tp>::epsilon()) break; __sum += __term; } return __numeric_constants<_Tp>::__pi_2() * __sum; } /** * @brief Return the complete elliptic integral of the first kind * @f$ K(k) @f$ using the Carlson formulation. * * The complete elliptic integral of the first kind is defined as * @f[ * K(k) = F(k,\pi/2) = \int_0^{\pi/2}\frac{d\theta} * {\sqrt{1 - k^2 sin^2\theta}} * @f] * where @f$ F(k,\phi) @f$ is the incomplete elliptic integral of the * first kind. * * @param __k The argument of the complete elliptic function. * @return The complete elliptic function of the first kind. */ template<typename _Tp> _Tp __comp_ellint_1(_Tp __k) { if (__isnan(__k)) return std::numeric_limits<_Tp>::quiet_NaN(); else if (std::abs(__k) >= _Tp(1)) return std::numeric_limits<_Tp>::quiet_NaN(); else return __ellint_rf(_Tp(0), _Tp(1) - __k * __k, _Tp(1)); } /** * @brief Return the incomplete elliptic integral of the first kind * @f$ F(k,\phi) @f$ using the Carlson formulation. * * The incomplete elliptic integral of the first kind is defined as * @f[ * F(k,\phi) = \int_0^{\phi}\frac{d\theta} * {\sqrt{1 - k^2 sin^2\theta}} * @f] * * @param __k The argument of the elliptic function. * @param __phi The integral limit argument of the elliptic function. * @return The elliptic function of the first kind. */ template<typename _Tp> _Tp __ellint_1(_Tp __k, _Tp __phi) { if (__isnan(__k) || __isnan(__phi)) return std::numeric_limits<_Tp>::quiet_NaN(); else if (std::abs(__k) > _Tp(1)) std::__throw_domain_error(__N("Bad argument in __ellint_1.")); else { // Reduce phi to -pi/2 < phi < +pi/2. const int __n = std::floor(__phi / __numeric_constants<_Tp>::__pi() + _Tp(0.5L)); const _Tp __phi_red = __phi - __n * __numeric_constants<_Tp>::__pi(); const _Tp __s = std::sin(__phi_red); const _Tp __c = std::cos(__phi_red); const _Tp __F = __s * __ellint_rf(__c * __c, _Tp(1) - __k * __k * __s * __s, _Tp(1)); if (__n == 0) return __F; else return __F + _Tp(2) * __n * __comp_ellint_1(__k); } } /** * @brief Return the complete elliptic integral of the second kind * @f$ E(k) @f$ by series expansion. * * The complete elliptic integral of the second kind is defined as * @f[ * E(k,\pi/2) = \int_0^{\pi/2}\sqrt{1 - k^2 sin^2\theta} * @f] * * This routine is not bad as long as |k| is somewhat smaller than 1 * but is not is good as the Carlson elliptic integral formulation. * * @param __k The argument of the complete elliptic function. * @return The complete elliptic function of the second kind. */ template<typename _Tp> _Tp __comp_ellint_2_series(_Tp __k) { const _Tp __kk = __k * __k; _Tp __term = __kk; _Tp __sum = __term; const unsigned int __max_iter = 1000; for (unsigned int __i = 2; __i < __max_iter; ++__i) { const _Tp __i2m = 2 * __i - 1; const _Tp __i2 = 2 * __i; __term *= __i2m * __i2m * __kk / (__i2 * __i2); if (__term < std::numeric_limits<_Tp>::epsilon()) break; __sum += __term / __i2m; } return __numeric_constants<_Tp>::__pi_2() * (_Tp(1) - __sum); } /** * @brief Return the Carlson elliptic function of the second kind * @f$ R_D(x,y,z) = R_J(x,y,z,z) @f$ where * @f$ R_J(x,y,z,p) @f$ is the Carlson elliptic function * of the third kind. * * The Carlson elliptic function of the second kind is defined by: * @f[ * R_D(x,y,z) = \frac{3}{2} \int_0^\infty * \frac{dt}{(t + x)^{1/2}(t + y)^{1/2}(t + z)^{3/2}} * @f] * * Based on Carlson's algorithms: * - B. C. Carlson Numer. Math. 33, 1 (1979) * - B. C. Carlson, Special Functions of Applied Mathematics (1977) * - Numerical Recipes in C, 2nd ed, pp. 261-269, * by Press, Teukolsky, Vetterling, Flannery (1992) * * @param __x The first of two symmetric arguments. * @param __y The second of two symmetric arguments. * @param __z The third argument. * @return The Carlson elliptic function of the second kind. */ template<typename _Tp> _Tp __ellint_rd(_Tp __x, _Tp __y, _Tp __z) { const _Tp __eps = std::numeric_limits<_Tp>::epsilon(); const _Tp __errtol = std::pow(__eps / _Tp(8), _Tp(1) / _Tp(6)); const _Tp __min = std::numeric_limits<_Tp>::min(); const _Tp __max = std::numeric_limits<_Tp>::max(); const _Tp __lolim = _Tp(2) / std::pow(__max, _Tp(2) / _Tp(3)); const _Tp __uplim = std::pow(_Tp(0.1L) * __errtol / __min, _Tp(2) / _Tp(3)); if (__x < _Tp(0) || __y < _Tp(0)) std::__throw_domain_error(__N("Argument less than zero " "in __ellint_rd.")); else if (__x + __y < __lolim || __z < __lolim) std::__throw_domain_error(__N("Argument too small " "in __ellint_rd.")); else { const _Tp __c0 = _Tp(1) / _Tp(4); const _Tp __c1 = _Tp(3) / _Tp(14); const _Tp __c2 = _Tp(1) / _Tp(6); const _Tp __c3 = _Tp(9) / _Tp(22); const _Tp __c4 = _Tp(3) / _Tp(26); _Tp __xn = __x; _Tp __yn = __y; _Tp __zn = __z; _Tp __sigma = _Tp(0); _Tp __power4 = _Tp(1); _Tp __mu; _Tp __xndev, __yndev, __zndev; const unsigned int __max_iter = 100; for (unsigned int __iter = 0; __iter < __max_iter; ++__iter) { __mu = (__xn + __yn + _Tp(3) * __zn) / _Tp(5); __xndev = (__mu - __xn) / __mu; __yndev = (__mu - __yn) / __mu; __zndev = (__mu - __zn) / __mu; _Tp __epsilon = std::max(std::abs(__xndev), std::abs(__yndev)); __epsilon = std::max(__epsilon, std::abs(__zndev)); if (__epsilon < __errtol) break; _Tp __xnroot = std::sqrt(__xn); _Tp __ynroot = std::sqrt(__yn); _Tp __znroot = std::sqrt(__zn); _Tp __lambda = __xnroot * (__ynroot + __znroot) + __ynroot * __znroot; __sigma += __power4 / (__znroot * (__zn + __lambda)); __power4 *= __c0; __xn = __c0 * (__xn + __lambda); __yn = __c0 * (__yn + __lambda); __zn = __c0 * (__zn + __lambda); } _Tp __ea = __xndev * __yndev; _Tp __eb = __zndev * __zndev; _Tp __ec = __ea - __eb; _Tp __ed = __ea - _Tp(6) * __eb; _Tp __ef = __ed + __ec + __ec; _Tp __s1 = __ed * (-__c1 + __c3 * __ed / _Tp(3) - _Tp(3) * __c4 * __zndev * __ef / _Tp(2)); _Tp __s2 = __zndev * (__c2 * __ef + __zndev * (-__c3 * __ec - __zndev * __c4 - __ea)); return _Tp(3) * __sigma + __power4 * (_Tp(1) + __s1 + __s2) / (__mu * std::sqrt(__mu)); } } /** * @brief Return the complete elliptic integral of the second kind * @f$ E(k) @f$ using the Carlson formulation. * * The complete elliptic integral of the second kind is defined as * @f[ * E(k,\pi/2) = \int_0^{\pi/2}\sqrt{1 - k^2 sin^2\theta} * @f] * * @param __k The argument of the complete elliptic function. * @return The complete elliptic function of the second kind. */ template<typename _Tp> _Tp __comp_ellint_2(_Tp __k) { if (__isnan(__k)) return std::numeric_limits<_Tp>::quiet_NaN(); else if (std::abs(__k) == 1) return _Tp(1); else if (std::abs(__k) > _Tp(1)) std::__throw_domain_error(__N("Bad argument in __comp_ellint_2.")); else { const _Tp __kk = __k * __k; return __ellint_rf(_Tp(0), _Tp(1) - __kk, _Tp(1)) - __kk * __ellint_rd(_Tp(0), _Tp(1) - __kk, _Tp(1)) / _Tp(3); } } /** * @brief Return the incomplete elliptic integral of the second kind * @f$ E(k,\phi) @f$ using the Carlson formulation. * * The incomplete elliptic integral of the second kind is defined as * @f[ * E(k,\phi) = \int_0^{\phi} \sqrt{1 - k^2 sin^2\theta} * @f] * * @param __k The argument of the elliptic function. * @param __phi The integral limit argument of the elliptic function. * @return The elliptic function of the second kind. */ template<typename _Tp> _Tp __ellint_2(_Tp __k, _Tp __phi) { if (__isnan(__k) || __isnan(__phi)) return std::numeric_limits<_Tp>::quiet_NaN(); else if (std::abs(__k) > _Tp(1)) std::__throw_domain_error(__N("Bad argument in __ellint_2.")); else { // Reduce phi to -pi/2 < phi < +pi/2. const int __n = std::floor(__phi / __numeric_constants<_Tp>::__pi() + _Tp(0.5L)); const _Tp __phi_red = __phi - __n * __numeric_constants<_Tp>::__pi(); const _Tp __kk = __k * __k; const _Tp __s = std::sin(__phi_red); const _Tp __ss = __s * __s; const _Tp __sss = __ss * __s; const _Tp __c = std::cos(__phi_red); const _Tp __cc = __c * __c; const _Tp __E = __s * __ellint_rf(__cc, _Tp(1) - __kk * __ss, _Tp(1)) - __kk * __sss * __ellint_rd(__cc, _Tp(1) - __kk * __ss, _Tp(1)) / _Tp(3); if (__n == 0) return __E; else return __E + _Tp(2) * __n * __comp_ellint_2(__k); } } /** * @brief Return the Carlson elliptic function * @f$ R_C(x,y) = R_F(x,y,y) @f$ where @f$ R_F(x,y,z) @f$ * is the Carlson elliptic function of the first kind. * * The Carlson elliptic function is defined by: * @f[ * R_C(x,y) = \frac{1}{2} \int_0^\infty * \frac{dt}{(t + x)^{1/2}(t + y)} * @f] * * Based on Carlson's algorithms: * - B. C. Carlson Numer. Math. 33, 1 (1979) * - B. C. Carlson, Special Functions of Applied Mathematics (1977) * - Numerical Recipes in C, 2nd ed, pp. 261-269, * by Press, Teukolsky, Vetterling, Flannery (1992) * * @param __x The first argument. * @param __y The second argument. * @return The Carlson elliptic function. */ template<typename _Tp> _Tp __ellint_rc(_Tp __x, _Tp __y) { const _Tp __min = std::numeric_limits<_Tp>::min(); const _Tp __max = std::numeric_limits<_Tp>::max(); const _Tp __lolim = _Tp(5) * __min; const _Tp __uplim = __max / _Tp(5); if (__x < _Tp(0) || __y < _Tp(0) || __x + __y < __lolim) std::__throw_domain_error(__N("Argument less than zero " "in __ellint_rc.")); else { const _Tp __c0 = _Tp(1) / _Tp(4); const _Tp __c1 = _Tp(1) / _Tp(7); const _Tp __c2 = _Tp(9) / _Tp(22); const _Tp __c3 = _Tp(3) / _Tp(10); const _Tp __c4 = _Tp(3) / _Tp(8); _Tp __xn = __x; _Tp __yn = __y; const _Tp __eps = std::numeric_limits<_Tp>::epsilon(); const _Tp __errtol = std::pow(__eps / _Tp(30), _Tp(1) / _Tp(6)); _Tp __mu; _Tp __sn; const unsigned int __max_iter = 100; for (unsigned int __iter = 0; __iter < __max_iter; ++__iter) { __mu = (__xn + _Tp(2) * __yn) / _Tp(3); __sn = (__yn + __mu) / __mu - _Tp(2); if (std::abs(__sn) < __errtol) break; const _Tp __lambda = _Tp(2) * std::sqrt(__xn) * std::sqrt(__yn) + __yn; __xn = __c0 * (__xn + __lambda); __yn = __c0 * (__yn + __lambda); } _Tp __s = __sn * __sn * (__c3 + __sn*(__c1 + __sn * (__c4 + __sn * __c2))); return (_Tp(1) + __s) / std::sqrt(__mu); } } /** * @brief Return the Carlson elliptic function @f$ R_J(x,y,z,p) @f$ * of the third kind. * * The Carlson elliptic function of the third kind is defined by: * @f[ * R_J(x,y,z,p) = \frac{3}{2} \int_0^\infty * \frac{dt}{(t + x)^{1/2}(t + y)^{1/2}(t + z)^{1/2}(t + p)} * @f] * * Based on Carlson's algorithms: * - B. C. Carlson Numer. Math. 33, 1 (1979) * - B. C. Carlson, Special Functions of Applied Mathematics (1977) * - Numerical Recipes in C, 2nd ed, pp. 261-269, * by Press, Teukolsky, Vetterling, Flannery (1992) * * @param __x The first of three symmetric arguments. * @param __y The second of three symmetric arguments. * @param __z The third of three symmetric arguments. * @param __p The fourth argument. * @return The Carlson elliptic function of the fourth kind. */ template<typename _Tp> _Tp __ellint_rj(_Tp __x, _Tp __y, _Tp __z, _Tp __p) { const _Tp __min = std::numeric_limits<_Tp>::min(); const _Tp __max = std::numeric_limits<_Tp>::max(); const _Tp __lolim = std::pow(_Tp(5) * __min, _Tp(1)/_Tp(3)); const _Tp __uplim = _Tp(0.3L) * std::pow(_Tp(0.2L) * __max, _Tp(1)/_Tp(3)); if (__x < _Tp(0) || __y < _Tp(0) || __z < _Tp(0)) std::__throw_domain_error(__N("Argument less than zero " "in __ellint_rj.")); else if (__x + __y < __lolim || __x + __z < __lolim || __y + __z < __lolim || __p < __lolim) std::__throw_domain_error(__N("Argument too small " "in __ellint_rj")); else { const _Tp __c0 = _Tp(1) / _Tp(4); const _Tp __c1 = _Tp(3) / _Tp(14); const _Tp __c2 = _Tp(1) / _Tp(3); const _Tp __c3 = _Tp(3) / _Tp(22); const _Tp __c4 = _Tp(3) / _Tp(26); _Tp __xn = __x; _Tp __yn = __y; _Tp __zn = __z; _Tp __pn = __p; _Tp __sigma = _Tp(0); _Tp __power4 = _Tp(1); const _Tp __eps = std::numeric_limits<_Tp>::epsilon(); const _Tp __errtol = std::pow(__eps / _Tp(8), _Tp(1) / _Tp(6)); _Tp __lambda, __mu; _Tp __xndev, __yndev, __zndev, __pndev; const unsigned int __max_iter = 100; for (unsigned int __iter = 0; __iter < __max_iter; ++__iter) { __mu = (__xn + __yn + __zn + _Tp(2) * __pn) / _Tp(5); __xndev = (__mu - __xn) / __mu; __yndev = (__mu - __yn) / __mu; __zndev = (__mu - __zn) / __mu; __pndev = (__mu - __pn) / __mu; _Tp __epsilon = std::max(std::abs(__xndev), std::abs(__yndev)); __epsilon = std::max(__epsilon, std::abs(__zndev)); __epsilon = std::max(__epsilon, std::abs(__pndev)); if (__epsilon < __errtol) break; const _Tp __xnroot = std::sqrt(__xn); const _Tp __ynroot = std::sqrt(__yn); const _Tp __znroot = std::sqrt(__zn); const _Tp __lambda = __xnroot * (__ynroot + __znroot) + __ynroot * __znroot; const _Tp __alpha1 = __pn * (__xnroot + __ynroot + __znroot) + __xnroot * __ynroot * __znroot; const _Tp __alpha2 = __alpha1 * __alpha1; const _Tp __beta = __pn * (__pn + __lambda) * (__pn + __lambda); __sigma += __power4 * __ellint_rc(__alpha2, __beta); __power4 *= __c0; __xn = __c0 * (__xn + __lambda); __yn = __c0 * (__yn + __lambda); __zn = __c0 * (__zn + __lambda); __pn = __c0 * (__pn + __lambda); } _Tp __ea = __xndev * (__yndev + __zndev) + __yndev * __zndev; _Tp __eb = __xndev * __yndev * __zndev; _Tp __ec = __pndev * __pndev; _Tp __e2 = __ea - _Tp(3) * __ec; _Tp __e3 = __eb + _Tp(2) * __pndev * (__ea - __ec); _Tp __s1 = _Tp(1) + __e2 * (-__c1 + _Tp(3) * __c3 * __e2 / _Tp(4) - _Tp(3) * __c4 * __e3 / _Tp(2)); _Tp __s2 = __eb * (__c2 / _Tp(2) + __pndev * (-__c3 - __c3 + __pndev * __c4)); _Tp __s3 = __pndev * __ea * (__c2 - __pndev * __c3) - __c2 * __pndev * __ec; return _Tp(3) * __sigma + __power4 * (__s1 + __s2 + __s3) / (__mu * std::sqrt(__mu)); } } /** * @brief Return the complete elliptic integral of the third kind * @f$ \Pi(k,\nu) = \Pi(k,\nu,\pi/2) @f$ using the * Carlson formulation. * * The complete elliptic integral of the third kind is defined as * @f[ * \Pi(k,\nu) = \int_0^{\pi/2} * \frac{d\theta} * {(1 - \nu \sin^2\theta)\sqrt{1 - k^2 \sin^2\theta}} * @f] * * @param __k The argument of the elliptic function. * @param __nu The second argument of the elliptic function. * @return The complete elliptic function of the third kind. */ template<typename _Tp> _Tp __comp_ellint_3(_Tp __k, _Tp __nu) { if (__isnan(__k) || __isnan(__nu)) return std::numeric_limits<_Tp>::quiet_NaN(); else if (__nu == _Tp(1)) return std::numeric_limits<_Tp>::infinity(); else if (std::abs(__k) > _Tp(1)) std::__throw_domain_error(__N("Bad argument in __comp_ellint_3.")); else { const _Tp __kk = __k * __k; return __ellint_rf(_Tp(0), _Tp(1) - __kk, _Tp(1)) + __nu * __ellint_rj(_Tp(0), _Tp(1) - __kk, _Tp(1), _Tp(1) - __nu) / _Tp(3); } } /** * @brief Return the incomplete elliptic integral of the third kind * @f$ \Pi(k,\nu,\phi) @f$ using the Carlson formulation. * * The incomplete elliptic integral of the third kind is defined as * @f[ * \Pi(k,\nu,\phi) = \int_0^{\phi} * \frac{d\theta} * {(1 - \nu \sin^2\theta) * \sqrt{1 - k^2 \sin^2\theta}} * @f] * * @param __k The argument of the elliptic function. * @param __nu The second argument of the elliptic function. * @param __phi The integral limit argument of the elliptic function. * @return The elliptic function of the third kind. */ template<typename _Tp> _Tp __ellint_3(_Tp __k, _Tp __nu, _Tp __phi) { if (__isnan(__k) || __isnan(__nu) || __isnan(__phi)) return std::numeric_limits<_Tp>::quiet_NaN(); else if (std::abs(__k) > _Tp(1)) std::__throw_domain_error(__N("Bad argument in __ellint_3.")); else { // Reduce phi to -pi/2 < phi < +pi/2. const int __n = std::floor(__phi / __numeric_constants<_Tp>::__pi() + _Tp(0.5L)); const _Tp __phi_red = __phi - __n * __numeric_constants<_Tp>::__pi(); const _Tp __kk = __k * __k; const _Tp __s = std::sin(__phi_red); const _Tp __ss = __s * __s; const _Tp __sss = __ss * __s; const _Tp __c = std::cos(__phi_red); const _Tp __cc = __c * __c; const _Tp __Pi = __s * __ellint_rf(__cc, _Tp(1) - __kk * __ss, _Tp(1)) + __nu * __sss * __ellint_rj(__cc, _Tp(1) - __kk * __ss, _Tp(1), _Tp(1) - __nu * __ss) / _Tp(3); if (__n == 0) return __Pi; else return __Pi + _Tp(2) * __n * __comp_ellint_3(__k, __nu); } } } // namespace __detail #if ! _GLIBCXX_USE_STD_SPEC_FUNCS && defined(_GLIBCXX_TR1_CMATH) } // namespace tr1 #endif _GLIBCXX_END_NAMESPACE_VERSION } #endif // _GLIBCXX_TR1_ELL_INTEGRAL_TCC