1 | // This file is part of Eigen, a lightweight C++ template library
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2 | // for linear algebra.
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3 | //
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4 | // Copyright (C) 2010 Jitse Niesen <jitse@maths.leeds.ac.uk>
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5 | //
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6 | // This Source Code Form is subject to the terms of the Mozilla
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7 | // Public License v. 2.0. If a copy of the MPL was not distributed
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8 | // with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
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9 |
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10 | #ifndef EIGEN_STEM_FUNCTION
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11 | #define EIGEN_STEM_FUNCTION
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12 |
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13 | namespace Eigen {
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14 |
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15 | /** \ingroup MatrixFunctions_Module
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16 | * \brief Stem functions corresponding to standard mathematical functions.
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17 | */
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18 | template <typename Scalar>
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19 | class StdStemFunctions
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20 | {
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21 | public:
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22 |
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23 | /** \brief The exponential function (and its derivatives). */
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24 | static Scalar exp(Scalar x, int)
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25 | {
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26 | return std::exp(x);
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27 | }
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28 |
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29 | /** \brief Cosine (and its derivatives). */
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30 | static Scalar cos(Scalar x, int n)
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31 | {
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32 | Scalar res;
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33 | switch (n % 4) {
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34 | case 0:
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35 | res = std::cos(x);
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36 | break;
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37 | case 1:
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38 | res = -std::sin(x);
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39 | break;
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40 | case 2:
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41 | res = -std::cos(x);
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42 | break;
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43 | case 3:
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44 | res = std::sin(x);
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45 | break;
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46 | }
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47 | return res;
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48 | }
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49 |
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50 | /** \brief Sine (and its derivatives). */
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51 | static Scalar sin(Scalar x, int n)
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52 | {
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53 | Scalar res;
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54 | switch (n % 4) {
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55 | case 0:
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56 | res = std::sin(x);
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57 | break;
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58 | case 1:
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59 | res = std::cos(x);
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60 | break;
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61 | case 2:
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62 | res = -std::sin(x);
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63 | break;
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64 | case 3:
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65 | res = -std::cos(x);
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66 | break;
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67 | }
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68 | return res;
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69 | }
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70 |
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71 | /** \brief Hyperbolic cosine (and its derivatives). */
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72 | static Scalar cosh(Scalar x, int n)
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73 | {
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74 | Scalar res;
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75 | switch (n % 2) {
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76 | case 0:
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77 | res = std::cosh(x);
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78 | break;
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79 | case 1:
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80 | res = std::sinh(x);
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81 | break;
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82 | }
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83 | return res;
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84 | }
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85 |
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86 | /** \brief Hyperbolic sine (and its derivatives). */
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87 | static Scalar sinh(Scalar x, int n)
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88 | {
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89 | Scalar res;
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90 | switch (n % 2) {
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91 | case 0:
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92 | res = std::sinh(x);
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93 | break;
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94 | case 1:
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95 | res = std::cosh(x);
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96 | break;
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97 | }
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98 | return res;
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99 | }
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100 |
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101 | }; // end of class StdStemFunctions
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102 |
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103 | } // end namespace Eigen
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104 |
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105 | #endif // EIGEN_STEM_FUNCTION
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