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1
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2 // (C) Copyright John Maddock 2006.
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3 // Use, modification and distribution are subject to the
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4 // Boost Software License, Version 1.0. (See accompanying file
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5 // LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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6
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7 #ifndef BOOST_MATH_SPECIAL_HERMITE_HPP
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8 #define BOOST_MATH_SPECIAL_HERMITE_HPP
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9
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10 #ifdef _MSC_VER
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11 #pragma once
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12 #endif
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13
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14 #include <boost/math/special_functions/math_fwd.hpp>
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15 #include <boost/math/tools/config.hpp>
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16 #include <boost/math/policies/error_handling.hpp>
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17
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18 namespace boost{
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19 namespace math{
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20
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21 // Recurrance relation for Hermite polynomials:
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22 template <class T1, class T2, class T3>
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23 inline typename tools::promote_args<T1, T2, T3>::type
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24 hermite_next(unsigned n, T1 x, T2 Hn, T3 Hnm1)
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25 {
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26 return (2 * x * Hn - 2 * n * Hnm1);
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27 }
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28
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29 namespace detail{
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30
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31 // Implement Hermite polynomials via recurrance:
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32 template <class T>
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33 T hermite_imp(unsigned n, T x)
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34 {
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35 T p0 = 1;
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36 T p1 = 2 * x;
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37
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38 if(n == 0)
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39 return p0;
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40
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41 unsigned c = 1;
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42
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43 while(c < n)
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44 {
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45 std::swap(p0, p1);
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46 p1 = hermite_next(c, x, p0, p1);
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47 ++c;
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48 }
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49 return p1;
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50 }
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51
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52 } // namespace detail
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53
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54 template <class T, class Policy>
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55 inline typename tools::promote_args<T>::type
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56 hermite(unsigned n, T x, const Policy&)
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57 {
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58 typedef typename tools::promote_args<T>::type result_type;
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59 typedef typename policies::evaluation<result_type, Policy>::type value_type;
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60 return policies::checked_narrowing_cast<result_type, Policy>(detail::hermite_imp(n, static_cast<value_type>(x)), "boost::math::hermite<%1%>(unsigned, %1%)");
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61 }
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62
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63 template <class T>
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64 inline typename tools::promote_args<T>::type
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65 hermite(unsigned n, T x)
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66 {
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67 return boost::math::hermite(n, x, policies::policy<>());
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68 }
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69
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70 } // namespace math
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71 } // namespace boost
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72
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73 #endif // BOOST_MATH_SPECIAL_HERMITE_HPP
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74
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75
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76
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