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1 ;; Generic interfaces for mathematical functions
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2
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3 ;; by Konrad Hinsen
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4 ;; last updated May 5, 2009
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5
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6 ;; Copyright (c) Konrad Hinsen, 2009. All rights reserved. The use
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7 ;; and distribution terms for this software are covered by the Eclipse
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8 ;; Public License 1.0 (http://opensource.org/licenses/eclipse-1.0.php)
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9 ;; which can be found in the file epl-v10.html at the root of this
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10 ;; distribution. By using this software in any fashion, you are
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11 ;; agreeing to be bound by the terms of this license. You must not
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12 ;; remove this notice, or any other, from this software.
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13
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14 (ns
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15 ^{:author "Konrad Hinsen"
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16 :doc "Generic math function interface
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17 This library defines generic versions of common mathematical
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18 functions such as sqrt or sin as multimethods that can be
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19 defined for any type."}
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20 clojure.contrib.generic.math-functions
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21 (:use [clojure.contrib.def :only (defmacro-)])
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22 (:require [clojure.contrib.generic.arithmetic :as ga]
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23 [clojure.contrib.generic.comparison :as gc]))
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24
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25 (defmacro- defmathfn-1
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26 [name]
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27 (let [java-symbol (symbol "java.lang.Math" (str name))]
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28 `(do
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29 (defmulti ~name
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30 ~(str "Return the " name " of x.")
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31 {:arglists '([~'x])}
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32 type)
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33 (defmethod ~name java.lang.Number
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34 [~'x]
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35 (~java-symbol ~'x)))))
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36
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37 (defn- two-types [x y] [(type x) (type y)])
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38
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39 (defmacro- defmathfn-2
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40 [name]
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41 (let [java-symbol (symbol "java.lang.Math" (str name))]
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42 `(do
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43 (defmulti ~name
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44 ~(str "Return the " name " of x and y.")
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45 {:arglists '([~'x ~'y])}
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46 two-types)
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47 (defmethod ~name [java.lang.Number java.lang.Number]
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48 [~'x ~'y]
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49 (~java-symbol ~'x ~'y)))))
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50
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51 ; List of math functions taken from
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52 ; http://java.sun.com/j2se/1.4.2/docs/api/java/lang/Math.html
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53 (defmathfn-1 abs)
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54 (defmathfn-1 acos)
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55 (defmathfn-1 asin)
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56 (defmathfn-1 atan)
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57 (defmathfn-2 atan2)
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58 (defmathfn-1 ceil)
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59 (defmathfn-1 cos)
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60 (defmathfn-1 exp)
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61 (defmathfn-1 floor)
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62 (defmathfn-1 log)
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63 (defmathfn-2 pow)
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64 (defmathfn-1 rint)
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65 (defmathfn-1 round)
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66 (defmathfn-1 sin)
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67 (defmathfn-1 sqrt)
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68 (defmathfn-1 tan)
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69
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70 ;
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71 ; Sign
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72 ;
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73 (defmulti sgn
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74 "Return the sign of x (-1, 0, or 1)."
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75 {:arglists '([x])}
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76 type)
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77
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78 (defmethod sgn :default
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79 [x]
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80 (cond (gc/zero? x) 0
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81 (gc/> x 0) 1
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82 :else -1))
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83
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84 ;
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85 ; Conjugation
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86 ;
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87 (defmulti conjugate
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88 "Return the conjugate of x."
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89 {:arglists '([x])}
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90 type)
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91
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92 (defmethod conjugate :default
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93 [x] x)
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94
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95 ;
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96 ; Square
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97 ;
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98 (defmulti sqr
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99 "Return the square of x."
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100 {:arglists '([x])}
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101 type)
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102
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103 (defmethod sqr :default
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104 [x]
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105 (ga/* x x))
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106
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107 ;
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108 ; Approximate equality for use with floating point types
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109 ;
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110 (defn approx=
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111 "Return true if the absolute value of the difference between x and y
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112 is less than eps."
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113 [x y eps]
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114 (gc/< (abs (ga/- x y)) eps))
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