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[/
Copyright (c) 2006 Xiaogang Zhang
Copyright (c) 2006 John Maddock
Use, modification and distribution are subject to the
Boost Software License, Version 1.0. (See accompanying file
LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
]
[section:ellint_carlson Elliptic Integrals - Carlson Form]
[heading Synopsis]
``
#include <boost/math/special_functions/ellint_rf.hpp>
``
namespace boost { namespace math {
template <class T1, class T2, class T3>
BOOST_MATH_GPU_ENABLED ``__sf_result`` ellint_rf(T1 x, T2 y, T3 z)
template <class T1, class T2, class T3, class ``__Policy``>
BOOST_MATH_GPU_ENABLED ``__sf_result`` ellint_rf(T1 x, T2 y, T3 z, const ``__Policy``&)
}} // namespaces
``
#include <boost/math/special_functions/ellint_rd.hpp>
``
namespace boost { namespace math {
template <class T1, class T2, class T3>
BOOST_MATH_GPU_ENABLED ``__sf_result`` ellint_rd(T1 x, T2 y, T3 z)
template <class T1, class T2, class T3, class ``__Policy``>
BOOST_MATH_GPU_ENABLED ``__sf_result`` ellint_rd(T1 x, T2 y, T3 z, const ``__Policy``&)
}} // namespaces
``
#include <boost/math/special_functions/ellint_rj.hpp>
``
namespace boost { namespace math {
template <class T1, class T2, class T3, class T4>
BOOST_MATH_GPU_ENABLED ``__sf_result`` ellint_rj(T1 x, T2 y, T3 z, T4 p)
template <class T1, class T2, class T3, class T4, class ``__Policy``>
BOOST_MATH_GPU_ENABLED ``__sf_result`` ellint_rj(T1 x, T2 y, T3 z, T4 p, const ``__Policy``&)
}} // namespaces
``
#include <boost/math/special_functions/ellint_rc.hpp>
``
namespace boost { namespace math {
template <class T1, class T2>
BOOST_MATH_GPU_ENABLED ``__sf_result`` ellint_rc(T1 x, T2 y)
template <class T1, class T2, class ``__Policy``>
BOOST_MATH_GPU_ENABLED ``__sf_result`` ellint_rc(T1 x, T2 y, const ``__Policy``&)
}} // namespaces
``
#include <boost/math/special_functions/ellint_rg.hpp>
``
namespace boost { namespace math {
template <class T1, class T2, class T3>
BOOST_MATH_GPU_ENABLED ``__sf_result`` ellint_rg(T1 x, T2 y, T3 z)
template <class T1, class T2, class T3, class ``__Policy``>
BOOST_MATH_GPU_ENABLED ``__sf_result`` ellint_rg(T1 x, T2 y, T3 z, const ``__Policy``&)
}} // namespaces
[heading Description]
These functions return Carlson's symmetrical elliptic integrals, the functions
have complicated behavior over all their possible domains, but the following
graph gives an idea of their behavior:
[graph ellint_carlson]
The return type of these functions is computed using the __arg_promotion_rules
when the arguments are of different types: otherwise the return is the same type
as the arguments.
template <class T1, class T2, class T3>
BOOST_MATH_GPU_ENABLED ``__sf_result`` ellint_rf(T1 x, T2 y, T3 z)
template <class T1, class T2, class T3, class ``__Policy``>
BOOST_MATH_GPU_ENABLED ``__sf_result`` ellint_rf(T1 x, T2 y, T3 z, const ``__Policy``&)
Returns Carlson's Elliptic Integral ['R[sub F]]:
[equation ellint9]
Requires that all of the arguments are non-negative, and at most
one may be zero. Otherwise returns the result of __domain_error.
[optional_policy]
template <class T1, class T2, class T3>
BOOST_MATH_GPU_ENABLED ``__sf_result`` ellint_rd(T1 x, T2 y, T3 z)
template <class T1, class T2, class T3, class ``__Policy``>
BOOST_MATH_GPU_ENABLED ``__sf_result`` ellint_rd(T1 x, T2 y, T3 z, const ``__Policy``&)
Returns Carlson's elliptic integral R[sub D]:
[equation ellint10]
Requires that x and y are non-negative, with at most one of them
zero, and that z >= 0. Otherwise returns the result of __domain_error.
[optional_policy]
template <class T1, class T2, class T3, class T4>
BOOST_MATH_GPU_ENABLED ``__sf_result`` ellint_rj(T1 x, T2 y, T3 z, T4 p)
template <class T1, class T2, class T3, class T4, class ``__Policy``>
BOOST_MATH_GPU_ENABLED ``__sf_result`` ellint_rj(T1 x, T2 y, T3 z, T4 p, const ``__Policy``&)
Returns Carlson's elliptic integral R[sub J]:
[equation ellint11]
Requires that x, y and z are non-negative, with at most one of them
zero, and that ['p != 0]. Otherwise returns the result of __domain_error.
[optional_policy]
When ['p < 0] the function returns the
[@http://en.wikipedia.org/wiki/Cauchy_principal_value Cauchy principal value]
using the relation:
[equation ellint17]
template <class T1, class T2>
BOOST_MATH_GPU_ENABLED ``__sf_result`` ellint_rc(T1 x, T2 y)
template <class T1, class T2, class ``__Policy``>
BOOST_MATH_GPU_ENABLED ``__sf_result`` ellint_rc(T1 x, T2 y, const ``__Policy``&)
Returns Carlson's elliptic integral R[sub C]:
[equation ellint12]
Requires that ['x > 0] and that ['y != 0].
Otherwise returns the result of __domain_error.
[optional_policy]
When ['y < 0] the function returns the
[@http://mathworld.wolfram.com/CauchyPrincipalValue.html Cauchy principal value]
using the relation:
[equation ellint18]
template <class T1, class T2, class T3>
BOOST_MATH_GPU_ENABLED ``__sf_result`` ellint_rg(T1 x, T2 y, T3 z)
template <class T1, class T2, class T3, class ``__Policy``>
BOOST_MATH_GPU_ENABLED ``__sf_result`` ellint_rg(T1 x, T2 y, T3 z, const ``__Policy``&)
Returns Carlson's elliptic integral ['R[sub G]:]
[equation ellint27]
Requires that x and y are non-negative, otherwise returns the result of __domain_error.
[optional_policy]
[heading Testing]
There are two sets of tests.
Spot tests compare selected values with test data given in:
[:B. C. Carlson, ['[@http://arxiv.org/abs/math.CA/9409227
Numerical computation of real or complex elliptic integrals]]. Numerical Algorithms,
Volume 10, Number 1 / March, 1995, pp 13-26.]
Random test data generated using NTL::RR at 1000-bit precision and our
implementation checks for rounding-errors and/or regressions.
There are also sanity checks that use the inter-relations between the integrals
to verify their correctness: see the above Carlson paper for details.
[heading Accuracy]
These functions are computed using only basic arithmetic operations, so
there isn't much variation in accuracy over differing platforms.
Note that only results for the widest floating-point type on the
system are given as narrower types have __zero_error. All values
are relative errors in units of epsilon.
[table_ellint_rc]
[table_ellint_rd]
[table_ellint_rg]
[table_ellint_rf]
[table_ellint_rj]
[heading Implementation]
The key of Carlson's algorithm [[link ellint_ref_carlson79 Carlson79]] is the
duplication theorem:
[equation ellint13]
By applying it repeatedly, ['x], ['y], ['z] get
closer and closer. When they are nearly equal, the special case equation
[equation ellint16]
is used. More specifically, ['[R F]] is evaluated from a Taylor series
expansion to the fifth order. The calculations of the other three integrals
are analogous, except for R[sub C] which can be computed from elementary functions.
For ['p < 0] in ['R[sub J](x, y, z, p)] and ['y < 0] in ['R[sub C](x, y)],
the integrals are singular and their
[@http://mathworld.wolfram.com/CauchyPrincipalValue.html Cauchy principal values]
are returned via the relations:
[equation ellint17]
[equation ellint18]
[endsect] [/section:ellint_carlson Elliptic Integrals - Carlson Form]
|
