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1 // Copyright (c) 2011, the Dart project authors. Please see the AUTHORS file | |
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. | |
4 | |
5 part of common; | |
6 | |
7 // Various math-related utility functions. | |
8 | |
9 class Math2 { | |
10 /// Computes the geometric mean of a set of numbers. | |
11 /// [minNumber] is optional (defaults to 0.001) anything smaller than this | |
12 /// will be changed to this value, eliminating infinite results. | |
13 static double geometricMean(List<double> numbers, | |
14 [double minNumber = 0.001]) { | |
15 double log = 0.0; | |
16 int nNumbers = 0; | |
17 for (int i = 0, n = numbers.length; i < n; i++) { | |
18 double number = numbers[i]; | |
19 if (number < minNumber) { | |
20 number = minNumber; | |
21 } | |
22 nNumbers++; | |
23 log += Math.log(number); | |
24 } | |
25 | |
26 return nNumbers > 0 ? Math.pow(Math.E, log / nNumbers) : 0.0; | |
27 } | |
28 | |
29 static int round(double d) { | |
30 return d.round(); | |
31 } | |
32 | |
33 static int floor(double d) { | |
34 return d.floor(); | |
35 } | |
36 | |
37 // TODO (olonho): use d.toStringAsFixed(precision) when implemented by DartVM | |
38 static String toStringAsFixed(num d, int precision) { | |
39 String dStr = d.toString(); | |
40 int pos = dStr.indexOf('.', 0); | |
41 int end = pos < 0 ? dStr.length : pos + precision; | |
42 if (precision > 0) { | |
43 end++; | |
44 } | |
45 if (end > dStr.length) { | |
46 end = dStr.length; | |
47 } | |
48 | |
49 return dStr.substring(0, end); | |
50 } | |
51 } | |
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