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1 // Copyright (c) 2012, the Dart project authors. Please see the AUTHORS file | 1 // Copyright (c) 2012, the Dart project authors. Please see the AUTHORS file |
2 // for details. All rights reserved. Use of this source code is governed by a | 2 // for details. All rights reserved. Use of this source code is governed by a |
3 // BSD-style license that can be found in the LICENSE file. | 3 // BSD-style license that can be found in the LICENSE file. |
4 | 4 |
5 /** | 5 /** |
6 * Mathematical constants and functions, plus a random number generator. | 6 * Mathematical constants and functions, plus a random number generator. |
7 * | 7 * |
8 * To use this library in your code: | 8 * To use this library in your code: |
9 * | 9 * |
10 * import 'dart:math'; | 10 * import 'dart:math'; |
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68 | 68 |
69 /** | 69 /** |
70 * Returns the lesser of two numbers. | 70 * Returns the lesser of two numbers. |
71 * | 71 * |
72 * Returns NaN if either argument is NaN. | 72 * Returns NaN if either argument is NaN. |
73 * The lesser of `-0.0` and `0.0` is `-0.0`. | 73 * The lesser of `-0.0` and `0.0` is `-0.0`. |
74 * If the arguments are otherwise equal (including int and doubles with the | 74 * If the arguments are otherwise equal (including int and doubles with the |
75 * same mathematical value) then it is unspecified which of the two arguments | 75 * same mathematical value) then it is unspecified which of the two arguments |
76 * is returned. | 76 * is returned. |
77 */ | 77 */ |
78 T min<T extends num>(T a, T b) { | 78 external T min<T extends num>(T a, T b); |
79 // These partially redundant type checks improve code quality for dart2js. | |
80 // Most of the improvement is at call sites from the inferred non-null num | |
81 // return type. | |
82 if (a is! num) throw new ArgumentError(a); | |
83 if (b is! num) throw new ArgumentError(b); | |
84 | |
85 if (a > b) return b; | |
86 if (a < b) return a; | |
87 if (b is double) { | |
88 // Special case for NaN and -0.0. If one argument is NaN return NaN. | |
89 // [min] must also distinguish between -0.0 and 0.0. | |
90 if (a is double) { | |
91 if (a == 0.0) { | |
92 // a is either 0.0 or -0.0. b is either 0.0, -0.0 or NaN. | |
93 // The following returns -0.0 if either a or b is -0.0, and it | |
94 // returns NaN if b is NaN. | |
95 return (a + b) * a * b; | |
96 } | |
97 } | |
98 // Check for NaN and b == -0.0. | |
99 if (a == 0 && b.isNegative || b.isNaN) return b; | |
100 return a; | |
101 } | |
102 return a; | |
103 } | |
104 | 79 |
105 /** | 80 /** |
106 * Returns the larger of two numbers. | 81 * Returns the larger of two numbers. |
107 * | 82 * |
108 * Returns NaN if either argument is NaN. | 83 * Returns NaN if either argument is NaN. |
109 * The larger of `-0.0` and `0.0` is `0.0`. If the arguments are | 84 * The larger of `-0.0` and `0.0` is `0.0`. If the arguments are |
110 * otherwise equal (including int and doubles with the same mathematical value) | 85 * otherwise equal (including int and doubles with the same mathematical value) |
111 * then it is unspecified which of the two arguments is returned. | 86 * then it is unspecified which of the two arguments is returned. |
112 */ | 87 */ |
113 T max<T extends num>(T a, T b) { | 88 external T max<T extends num>(T a, T b); |
114 // These partially redundant type checks improve code quality for dart2js. | |
115 // Most of the improvement is at call sites from the inferred non-null num | |
116 // return type. | |
117 if (a is! num) throw new ArgumentError(a); | |
118 if (b is! num) throw new ArgumentError(b); | |
119 | |
120 if (a > b) return a; | |
121 if (a < b) return b; | |
122 if (b is double) { | |
123 // Special case for NaN and -0.0. If one argument is NaN return NaN. | |
124 // [max] must also distinguish between -0.0 and 0.0. | |
125 if (a is double) { | |
126 if (a == 0.0) { | |
127 // a is either 0.0 or -0.0. b is either 0.0, -0.0, or NaN. | |
128 // The following returns 0.0 if either a or b is 0.0, and it | |
129 // returns NaN if b is NaN. | |
130 return a + b; | |
131 } | |
132 } | |
133 // Check for NaN. | |
134 if (b.isNaN) return b; | |
135 return a; | |
136 } | |
137 // max(-0.0, 0) must return 0. | |
138 if (b == 0 && a.isNegative) return b; | |
139 return a; | |
140 } | |
141 | 89 |
142 /** | 90 /** |
143 * A variant of [atan]. | 91 * A variant of [atan]. |
144 * | 92 * |
145 * Converts both arguments to [double]s. | 93 * Converts both arguments to [double]s. |
146 * | 94 * |
147 * Returns the angle in radians between the positive x-axis | 95 * Returns the angle in radians between the positive x-axis |
148 * and the vector ([b],[a]). | 96 * and the vector ([b],[a]). |
149 * The result is in the range -PI..PI. | 97 * The result is in the range -PI..PI. |
150 * | 98 * |
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261 */ | 209 */ |
262 external double exp(num x); | 210 external double exp(num x); |
263 | 211 |
264 /** | 212 /** |
265 * Converts [x] to a [double] and returns the natural logarithm of the value. | 213 * Converts [x] to a [double] and returns the natural logarithm of the value. |
266 * | 214 * |
267 * Returns negative infinity if [x] is equal to zero. | 215 * Returns negative infinity if [x] is equal to zero. |
268 * Returns NaN if [x] is NaN or less than zero. | 216 * Returns NaN if [x] is NaN or less than zero. |
269 */ | 217 */ |
270 external double log(num x); | 218 external double log(num x); |
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