1 /* 2 * Copyright (c) 2001, 2007, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 /** 26 ** This file contains a few classes that represent number sequence, 27 ** x1, x2, x3, ..., xN, and can calculate their avg, max, and sd. 28 ** 29 ** Here's a quick description of the classes: 30 ** 31 ** AbsSeq: abstract superclass 32 ** NumberSeq: the sequence is assumed to be very long and the 33 ** maximum, avg, sd, davg, and dsd are calculated over all its elements 34 ** TruncatedSeq: this class keeps track of the last L elements 35 ** of the sequence and calculates avg, max, and sd only over them 36 **/ 37 38 #define DEFAULT_ALPHA_VALUE 0.7 39 40 class AbsSeq { 41 private: 42 void init(double alpha); 43 44 protected: 45 int _num; // the number of elements in the sequence 46 double _sum; // the sum of the elements in the sequence 47 double _sum_of_squares; // the sum of squares of the elements in the sequence 48 49 double _davg; // decaying average 50 double _dvariance; // decaying variance 51 double _alpha; // factor for the decaying average / variance 52 53 // This is what we divide with to get the average. In a standard 54 // number sequence, this should just be the number of elements in it. 55 virtual double total() const { return (double) _num; }; 56 57 public: 58 AbsSeq(double alpha = DEFAULT_ALPHA_VALUE); 59 60 virtual void add(double val); // adds a new element to the sequence 61 void add(unsigned val) { add((double) val); } 62 virtual double maximum() const = 0; // maximum element in the sequence 63 virtual double last() const = 0; // last element added in the sequence 64 65 // the number of elements in the sequence 66 int num() const { return _num; } 67 // the sum of the elements in the sequence 68 double sum() const { return _sum; } 69 70 double avg() const; // the average of the sequence 71 double variance() const; // the variance of the sequence 72 double sd() const; // the standard deviation of the sequence 73 74 double davg() const; // decaying average 75 double dvariance() const; // decaying variance 76 double dsd() const; // decaying "standard deviation" 77 78 // Debugging/Printing 79 virtual void dump(); 80 virtual void dump_on(outputStream* s); 81 }; 82 83 class NumberSeq: public AbsSeq { 84 private: 85 bool check_nums(NumberSeq* total, int n, NumberSeq** parts); 86 87 protected: 88 double _last; 89 double _maximum; // keep track of maximum value 90 91 public: 92 NumberSeq(double alpha = DEFAULT_ALPHA_VALUE); 93 NumberSeq(NumberSeq* total, int n_parts, NumberSeq** parts); 94 95 virtual void add(double val); 96 virtual double maximum() const { return _maximum; } 97 virtual double last() const { return _last; } 98 99 // Debugging/Printing 100 virtual void dump_on(outputStream* s); 101 }; 102 103 class TruncatedSeq: public AbsSeq { 104 private: 105 enum PrivateConstants { 106 DefaultSeqLength = 10 107 }; 108 void init(); 109 protected: 110 double *_sequence; // buffers the last L elements in the sequence 111 int _length; // this is L 112 int _next; // oldest slot in the array, i.e. next to be overwritten 113 114 public: 115 // accepts a value for L 116 TruncatedSeq(int length = DefaultSeqLength, 117 double alpha = DEFAULT_ALPHA_VALUE); 118 virtual void add(double val); 119 virtual double maximum() const; 120 virtual double last() const; // the last value added to the sequence 121 122 double oldest() const; // the oldest valid value in the sequence 123 double predict_next() const; // prediction based on linear regression 124 125 // Debugging/Printing 126 virtual void dump_on(outputStream* s); 127 };