dgrove@google.com
4bc64b8c2b
git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart@7 260f80e4-7a28-3924-810f-c04153c831b5
50 lines
1.4 KiB
Dart
50 lines
1.4 KiB
Dart
// Copyright (c) 2011, the Dart project authors. Please see the AUTHORS file
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// for details. All rights reserved. Use of this source code is governed by a
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// BSD-style license that can be found in the LICENSE file.
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// Various math-related utility functions.
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class Math2 {
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/// Computes the geometric mean of a set of numbers.
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/// [minNumber] is optional (defaults to 0.001) anything smaller than this
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/// will be changed to this value, eliminating infinite results.
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static double geometricMean(Array<double> numbers,
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[double minNumber = 0.001]) {
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double log = 0.0;
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int nNumbers = 0;
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for (int i = 0, n = numbers.length; i < n; i++) {
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double number = numbers[i];
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if (number < minNumber) {
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number = minNumber;
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}
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nNumbers++;
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log += Math.log(number);
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}
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return nNumbers > 0 ? Math.pow(Math.E, log / nNumbers) : 0.0;
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}
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static int round(double d) {
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return d.round().toInt();
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}
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static int floor(double d) {
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return d.floor().toInt();
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}
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// TODO (olonho): use d.toStringAsFixed(precision) when implemented by DartVM
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static String toStringAsFixed(num d, int precision) {
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String dStr = d.toString();
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int pos = dStr.indexOf('.', 0);
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int end = pos < 0 ? dStr.length : pos + precision;
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if (precision > 0) {
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end++;
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}
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if (end > dStr.length) {
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end = dStr.length;
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}
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return dStr.substring(0, end);
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}
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}
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