f216854453
The functions are conventionally called i0e and i1e. The exponentially scaled version is more numerically stable. The standard Bessel functions can be obtained as i0(x) = exp(|x|) i0e(x) The code is ported from Cephes and tested against SciPy.
71 lines
3.2 KiB
C++
71 lines
3.2 KiB
C++
// This file is part of Eigen, a lightweight C++ template library
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// for linear algebra.
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//
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// Copyright (C) 2016 Gael Guennebaud <gael.guennebaud@inria.fr>
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//
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// This Source Code Form is subject to the terms of the Mozilla
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// Public License v. 2.0. If a copy of the MPL was not distributed
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// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
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#ifndef EIGEN_SPECIALFUNCTIONS_PACKETMATH_H
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#define EIGEN_SPECIALFUNCTIONS_PACKETMATH_H
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namespace Eigen {
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namespace internal {
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/** \internal \returns the ln(|gamma(\a a)|) (coeff-wise) */
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template<typename Packet> EIGEN_DECLARE_FUNCTION_ALLOWING_MULTIPLE_DEFINITIONS
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Packet plgamma(const Packet& a) { using numext::lgamma; return lgamma(a); }
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/** \internal \returns the derivative of lgamma, psi(\a a) (coeff-wise) */
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template<typename Packet> EIGEN_DECLARE_FUNCTION_ALLOWING_MULTIPLE_DEFINITIONS
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Packet pdigamma(const Packet& a) { using numext::digamma; return digamma(a); }
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/** \internal \returns the zeta function of two arguments (coeff-wise) */
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template<typename Packet> EIGEN_DECLARE_FUNCTION_ALLOWING_MULTIPLE_DEFINITIONS
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Packet pzeta(const Packet& x, const Packet& q) { using numext::zeta; return zeta(x, q); }
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/** \internal \returns the polygamma function (coeff-wise) */
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template<typename Packet> EIGEN_DECLARE_FUNCTION_ALLOWING_MULTIPLE_DEFINITIONS
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Packet ppolygamma(const Packet& n, const Packet& x) { using numext::polygamma; return polygamma(n, x); }
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/** \internal \returns the erf(\a a) (coeff-wise) */
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template<typename Packet> EIGEN_DECLARE_FUNCTION_ALLOWING_MULTIPLE_DEFINITIONS
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Packet perf(const Packet& a) { using numext::erf; return erf(a); }
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/** \internal \returns the erfc(\a a) (coeff-wise) */
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template<typename Packet> EIGEN_DECLARE_FUNCTION_ALLOWING_MULTIPLE_DEFINITIONS
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Packet perfc(const Packet& a) { using numext::erfc; return erfc(a); }
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/** \internal \returns the incomplete gamma function igamma(\a a, \a x) */
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template<typename Packet> EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE
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Packet pigamma(const Packet& a, const Packet& x) { using numext::igamma; return igamma(a, x); }
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/** \internal \returns the complementary incomplete gamma function igammac(\a a, \a x) */
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template<typename Packet> EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE
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Packet pigammac(const Packet& a, const Packet& x) { using numext::igammac; return igammac(a, x); }
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/** \internal \returns the complementary incomplete gamma function betainc(\a a, \a b, \a x) */
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template<typename Packet> EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE
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Packet pbetainc(const Packet& a, const Packet& b,const Packet& x) { using numext::betainc; return betainc(a, b, x); }
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/** \internal \returns the exponentially scaled modified Bessel function of
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* order zero i0e(\a a) (coeff-wise) */
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template <typename Packet>
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EIGEN_DEVICE_FUNC EIGEN_DECLARE_FUNCTION_ALLOWING_MULTIPLE_DEFINITIONS
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Packet pi0e(const Packet& x) { using numext::i0e; return i0e(x); }
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/** \internal \returns the exponentially scaled modified Bessel function of
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* order one i1e(\a a) (coeff-wise) */
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template <typename Packet>
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EIGEN_DEVICE_FUNC EIGEN_DECLARE_FUNCTION_ALLOWING_MULTIPLE_DEFINITIONS
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Packet pi1e(const Packet& x) { using numext::i1e; return i1e(x); }
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} // end namespace internal
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} // end namespace Eigen
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#endif // EIGEN_SPECIALFUNCTIONS_PACKETMATH_H
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