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