├── CODE_OF_CONDUCT.md ├── CHANGELOG.md ├── README.md ├── src ├── RunningStat.php └── PSquare.php └── COPYING /CODE_OF_CONDUCT.md: -------------------------------------------------------------------------------- 1 | The development of this software is covered by a [Code of Conduct](https://www.mediawiki.org/wiki/Special:MyLanguage/Code_of_Conduct). 2 | 3 | -------------------------------------------------------------------------------- /CHANGELOG.md: -------------------------------------------------------------------------------- 1 | # Changelog 2 | 3 | ## v2.2.0 4 | 5 | Added: 6 | 7 | * Add native type declarations and enable strict_types (Umherirrender) 8 | * Add missing documentation to class properties (Umherirrender) 9 | 10 | Changed: 11 | 12 | * Raise required PHP to 8.1+ (Reedy, Umherirrender) 13 | 14 | ## v2.1.0 15 | 16 | Added: 17 | 18 | * PSquare: Implement `__serialize()` and `__unserialize()` (Timo Tijhof) 19 | 20 | ## v2.0.0 21 | 22 | Removed: 23 | 24 | * Remove `RunningStat` namespace alias (Reedy) 25 | 26 | Fixed: 27 | 28 | * RunningStat: Remove workaround for resolved PHP 5.6 bug (Ammarpad) 29 | 30 | Changed: 31 | 32 | * Switch autoloader from classmap to PSR-4 (Kunal Mehta) 33 | * Raise required PHP to 7.0+ (Reedy) 34 | 35 | ## v1.2.1 36 | 37 | Fixed: 38 | 39 | * Fix `RelPath\RelPath` to extend `Wikimedia\RelPath` not `PSquare` (Reedy) 40 | 41 | ## v1.2.0 42 | 43 | Added: 44 | 45 | * Rename namespace from `RunningStat` to `Wikimedia` with compat alias (Reedy) 46 | 47 | ## v1.1.0 48 | 49 | Added: 50 | 51 | * Add `PSquare` class for online percentile estimation (Ori Livneh) 52 | 53 | Changed: 54 | 55 | * Rename `RunningStat::push()` to `RunningStat::addObservation()` (Ori Livneh) 56 | 57 | ## v1.0.0 58 | 59 | Initial release. -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | RunningStat 2 | =========== 3 | 4 | RunningStat computes the central tendency, shape, and extrema of a set of 5 | points online, in constant space. It uses a neat one-pass algorithm for 6 | calculating variance, described here: 7 | 8 | 9 | This particular implementation adapts a sample C++ implementation by John D. 10 | Cook to PHP. See also: 11 | 12 | * 13 | * 14 | 15 | RunningStat instances can be combined. The resultant RunningStat has the same 16 | state it would have had if it had been used to accumulate each point. This 17 | property is attractive because it allows separate threads of execution to 18 | process a stream in parallel. More importantly, individual points can be 19 | accumulated in stages, without loss of fidelity, at intermediate points in the 20 | aggregation process. JavaScript profiling samples can be accumulated in the 21 | user's browser and be combined with measurements from other browsers on the 22 | profiling data aggregator. Functions that are called multiple times in the 23 | course of a profiled web request can be accumulated in MediaWiki prior to being 24 | transmitted to the profiling data aggregator. 25 | 26 | Usage 27 | ----- 28 | Here is how you use it: 29 | 30 | ```php 31 | use Wikimedia\RunningStat; 32 | 33 | $rstat = new RunningStat(); 34 | foreach ( [ 35 | 49.7168, 74.3804, 7.0115, 96.5769, 34.9458, 36 | 36.9947, 33.8926, 89.0774, 23.7745, 73.5154, 37 | 86.1322, 53.2124, 16.2046, 73.5130, 10.4209, 38 | 42.7299, 49.3330, 47.0215, 34.9950, 18.2914, 39 | ] as $sample ) { 40 | $rstat->addObservation( $sample ); 41 | } 42 | 43 | 44 | printf( 45 | "n = %d; min = %.2f; max = %.2f; mean = %.2f; variance = %.2f; stddev = %.2f\n", 46 | count( $rstat ), 47 | $rstat->min, 48 | $rstat->max, 49 | $rstat->getMean(), 50 | $rstat->getVariance(), 51 | $rstat->getStdDev() 52 | ); 53 | // Output: 54 | // n = 20; min = 7.01; max = 96.58; mean = 47.59; variance = 725.71; stddev = 26.94 55 | ``` 56 | 57 | License 58 | ------- 59 | GPL-2.0-or-later 60 | -------------------------------------------------------------------------------- /src/RunningStat.php: -------------------------------------------------------------------------------- 1 | 8 | */ 9 | 10 | namespace Wikimedia; 11 | 12 | /** 13 | * Compute running mean, variance, and extrema of a stream of numbers. 14 | * 15 | * RunningStat instances are accumulator-like objects that provide a set of 16 | * continuously-updated summary statistics for a stream of numbers, without 17 | * requiring that each value be stored. The measures it provides are the 18 | * arithmetic mean, variance, standard deviation, and extrema (min and max); 19 | * together they describe the central tendency and statistical dispersion of a 20 | * set of values. 21 | * 22 | * One RunningStat instance can be merged into another; the resultant 23 | * RunningStat has the state it would have had if it had accumulated each 24 | * individual point. This allows data to be summarized in parallel and in 25 | * stages without loss of fidelity. 26 | * 27 | * Based on a C++ implementation by John D. Cook: 28 | * 29 | * - 30 | * - 31 | * 32 | * The in-line documentation for this class incorporates content from the 33 | * English Wikipedia articles "Variance", "Algorithms for calculating 34 | * variance", and "Standard deviation". 35 | */ 36 | class RunningStat { 37 | /** @var int Number of samples. */ 38 | public int $n = 0; 39 | /** @var float The first moment (or mean, or expected value). */ 40 | public float $m1 = 0.0; 41 | /** @var float The second central moment (or variance). */ 42 | public float $m2 = 0.0; 43 | /** @var float The least value in the set. */ 44 | public float $min = INF; 45 | /** @var float The greatest value in the set. */ 46 | public float $max = -INF; 47 | 48 | /** 49 | * Count the number of accumulated values. 50 | */ 51 | public function getCount(): int { 52 | return $this->n; 53 | } 54 | 55 | /** 56 | * Add a number to the data set. 57 | * 58 | * @param int|float $x Value to add 59 | */ 60 | public function addObservation( int|float $x ): void { 61 | $x = (float)$x; 62 | 63 | $this->min = min( $this->min, $x ); 64 | $this->max = max( $this->max, $x ); 65 | 66 | $n1 = $this->n; 67 | $this->n++; 68 | $delta = $x - $this->m1; 69 | $delta_n = $delta / $this->n; 70 | $this->m1 += $delta_n; 71 | $this->m2 += $delta * $delta_n * $n1; 72 | } 73 | 74 | /** 75 | * Get the mean, or expected value. 76 | * 77 | * The arithmetic mean is the sum of all measurements divided by the number 78 | * of observations in the data set. 79 | */ 80 | public function getMean(): float { 81 | return $this->m1; 82 | } 83 | 84 | /** 85 | * Get the estimated variance. 86 | * 87 | * Variance measures how far a set of numbers is spread out. A small 88 | * variance indicates that the data points tend to be very close to the 89 | * mean (and hence to each other), while a high variance indicates that the 90 | * data points are very spread out from the mean and from each other. 91 | * 92 | * @return float Estimated variance 93 | */ 94 | public function getVariance(): float { 95 | if ( $this->n === 0 ) { 96 | // The variance of the empty set is undefined. 97 | return NAN; 98 | } elseif ( $this->n === 1 ) { 99 | return 0.0; 100 | } else { 101 | return $this->m2 / ( $this->n - 1.0 ); 102 | } 103 | } 104 | 105 | /** 106 | * Get the estimated standard deviation. 107 | * 108 | * The standard deviation of a statistical population is the square root of 109 | * its variance. It shows how much variation from the mean exists. In 110 | * addition to expressing the variability of a population, the standard 111 | * deviation is commonly used to measure confidence in statistical conclusions. 112 | * 113 | * @return float Estimated standard deviation 114 | */ 115 | public function getStdDev(): float { 116 | return sqrt( $this->getVariance() ); 117 | } 118 | 119 | /** 120 | * Merge another RunningStat instance into this instance. 121 | * 122 | * This instance then has the state it would have had if all the data had 123 | * been accumulated by it alone. 124 | * 125 | * @param RunningStat $other RunningStat instance to merge into this one 126 | */ 127 | public function merge( RunningStat $other ): void { 128 | // If the other RunningStat is empty, there's nothing to do. 129 | if ( $other->n === 0 ) { 130 | return; 131 | } 132 | 133 | // If this RunningStat is empty, copy values from other RunningStat. 134 | if ( $this->n === 0 ) { 135 | $this->n = $other->n; 136 | $this->m1 = $other->m1; 137 | $this->m2 = $other->m2; 138 | $this->min = $other->min; 139 | $this->max = $other->max; 140 | return; 141 | } 142 | 143 | $n = $this->n + $other->n; 144 | $delta = $other->m1 - $this->m1; 145 | $delta2 = $delta * $delta; 146 | 147 | $this->m1 = ( ( $this->n * $this->m1 ) + ( $other->n * $other->m1 ) ) / $n; 148 | $this->m2 = $this->m2 + $other->m2 + ( $delta2 * $this->n * $other->n / $n ); 149 | $this->min = min( $this->min, $other->min ); 150 | $this->max = max( $this->max, $other->max ); 151 | $this->n = $n; 152 | } 153 | } 154 | -------------------------------------------------------------------------------- /src/PSquare.php: -------------------------------------------------------------------------------- 1 | 8 | */ 9 | 10 | namespace Wikimedia; 11 | 12 | /** 13 | * Represents a running, online estimate of a p-quantile for a series 14 | * of observations using the P-squared algorithm. 15 | * 16 | * The algorithm is from "The P-Square Algorithm for Dynamic Calculation of 17 | * Percentiles and Histograms without Storing Observations," Communications of 18 | * the ACM, October 1985 by R. Jain and I. Chlamtac. 19 | */ 20 | class PSquare { 21 | /** 22 | * Percentile to estimate. 23 | * @var float $p 24 | */ 25 | private float $p; 26 | 27 | /** 28 | * Position of each marker. 29 | * @var int[] $positions 30 | */ 31 | private array $positions; 32 | 33 | /** 34 | * Desired position of each marker. 35 | * @var float[] $desired 36 | */ 37 | private array $desired; 38 | 39 | /** @var float[] $increments */ 40 | private array $increments; 41 | 42 | /** 43 | * Number of observations. 44 | * @var int $numObservations 45 | */ 46 | private int $numObservations = 0; 47 | 48 | /** 49 | * Height of each marker. 50 | * @var float[] $heights 51 | */ 52 | private array $heights = []; 53 | 54 | /** 55 | * @param float $p the percentile (defaults to 0.5, or median). 56 | */ 57 | public function __construct( float $p = 0.5 ) { 58 | $this->p = $p; 59 | $this->positions = [ 0, 1, 2, 3, 4 ]; 60 | $this->desired = [ 0, ( 2 * $p ), ( 4 * $p ), 2 + ( 2 * $p ), 4 ]; 61 | $this->increments = [ 0, ( $p / 2 ), $p, ( ( 1 + $p ) / 2 ), 1 ]; 62 | } 63 | 64 | /** 65 | * Export state, e.g. for serializing and caching. 66 | * 67 | * @return array 68 | */ 69 | public function __serialize(): array { 70 | return [ 71 | 'percentile' => $this->p, 72 | 'positions' => $this->positions, 73 | 'desired' => $this->desired, 74 | 'increments' => $this->increments, 75 | 'numObservations' => $this->numObservations, 76 | 'heights' => $this->heights, 77 | ]; 78 | } 79 | 80 | public function __unserialize( array $data ): void { 81 | $this->p = $data['percentile']; 82 | $this->positions = $data['positions']; 83 | $this->desired = $data['desired']; 84 | $this->increments = $data['increments']; 85 | $this->numObservations = $data['numObservations']; 86 | $this->heights = $data['heights']; 87 | } 88 | 89 | /** 90 | * Get the total number of accumulated observations. 91 | */ 92 | public function getCount(): int { 93 | return $this->numObservations; 94 | } 95 | 96 | /** 97 | * Add an observation. 98 | * 99 | * @param int|float $x Value to add 100 | */ 101 | public function addObservation( int|float $x ): void { 102 | $this->numObservations++; 103 | 104 | if ( $this->numObservations <= 5 ) { 105 | $this->heights[] = $x; 106 | if ( $this->numObservations === 5 ) { 107 | sort( $this->heights ); 108 | } 109 | return; 110 | } 111 | 112 | if ( $x < $this->heights[0] ) { 113 | $this->heights[0] = $x; 114 | $k = 0; 115 | } elseif ( $x >= $this->heights[4] ) { 116 | $this->heights[4] = $x; 117 | $k = 3; 118 | } else { 119 | for ( $i = 1; $i < 5; $i++ ) { 120 | if ( $x < $this->heights[$i] ) { 121 | $k = $i - 1; 122 | break; 123 | } 124 | } 125 | } 126 | 127 | // @phan-suppress-next-line PhanPossiblyUndeclaredVariable 128 | for ( $i = $k + 1; $i < 5; $i++ ) { 129 | $this->positions[$i]++; 130 | } 131 | 132 | for ( $i = 0; $i < 5; $i++ ) { 133 | $this->desired[$i] += $this->increments[$i]; 134 | } 135 | 136 | for ( $i = 1; $i < 4; $i++ ) { 137 | $n = $this->positions[$i]; 138 | $nPrev = $this->positions[$i - 1]; 139 | $nNext = $this->positions[$i + 1]; 140 | 141 | $d = $this->desired[$i] - $n; 142 | 143 | if ( ( $d >= 1 && $nNext - $n > 1 ) || ( $d <= -1 && $nPrev - $n < -1 ) ) { 144 | $d = ( $d < 0 ) ? -1 : 1; 145 | 146 | $q = $this->computeParabolic( $i, $d ); 147 | $qPrev = $this->heights[$i - 1]; 148 | $qNext = $this->heights[$i + 1]; 149 | 150 | if ( $qPrev < $q && $q < $qNext ) { 151 | $this->heights[$i] = $q; 152 | } else { 153 | $this->heights[$i] = $this->computeLinear( $i, $d ); 154 | } 155 | 156 | $this->positions[$i] += $d; 157 | } 158 | } 159 | } 160 | 161 | /** 162 | * Use piecewise parabolic prediction to predict the ideal 163 | * height of a marker. 164 | * 165 | * @param int $i index of marker to adjust 166 | * @param int $d always -1 or 1 167 | * @return float ideal height of marker 168 | */ 169 | private function computeParabolic( int $i, int $d ): float { 170 | $q = $this->heights[$i]; 171 | $qPrev = $this->heights[$i - 1]; 172 | $qNext = $this->heights[$i + 1]; 173 | 174 | $n = $this->positions[$i]; 175 | $nPrev = $this->positions[$i - 1]; 176 | $nNext = $this->positions[$i + 1]; 177 | 178 | return ( $q + 179 | $d / ( $nNext - $nPrev ) * 180 | ( 181 | ( $n - $nPrev + $d ) * ( $qNext - $q ) / ( $nNext - $n ) + 182 | ( $nNext - $n - $d ) * ( $q - $qPrev ) / ( $n - $nPrev ) 183 | ) 184 | ); 185 | } 186 | 187 | /** 188 | * Linear formula to predict ideal position of a marker. 189 | * 190 | * @param int $i index of marker to adjust 191 | * @param int $d always -1 or 1 192 | * @return float ideal height of marker 193 | */ 194 | private function computeLinear( int $i, int $d ): float { 195 | $q = $this->heights[$i]; 196 | $n = $this->positions[$i]; 197 | return ( $q + $d * 198 | ( $this->heights[$i + $d] - $q ) / 199 | ( $this->positions[$i + $d] - $n ) 200 | ); 201 | } 202 | 203 | /** 204 | * Get the estimated p-quantile value. 205 | */ 206 | public function getValue(): float { 207 | // If we have five samples or fewer, fall back to a naive method. 208 | if ( $this->getCount() <= 5 ) { 209 | sort( $this->heights ); 210 | $i = $this->p * count( $this->heights ); 211 | $index = (int)$i; 212 | if ( $i === floor( $i ) ) { 213 | return ( $this->heights[$index - 1] + $this->heights[$index] ) / 2; 214 | } else { 215 | return $this->heights[$index]; 216 | } 217 | } 218 | 219 | return $this->heights[2]; 220 | } 221 | } 222 | -------------------------------------------------------------------------------- /COPYING: -------------------------------------------------------------------------------- 1 | GNU GENERAL PUBLIC LICENSE 2 | Version 2, June 1991 3 | 4 | Copyright (C) 1989, 1991 Free Software Foundation, Inc., 5 | 6 | Everyone is permitted to copy and distribute verbatim copies 7 | of this license document, but changing it is not allowed. 8 | 9 | Preamble 10 | 11 | The licenses for most software are designed to take away your 12 | freedom to share and change it. By contrast, the GNU General Public 13 | License is intended to guarantee your freedom to share and change free 14 | software--to make sure the software is free for all its users. This 15 | General Public License applies to most of the Free Software 16 | Foundation's software and to any other program whose authors commit to 17 | using it. (Some other Free Software Foundation software is covered by 18 | the GNU Lesser General Public License instead.) You can apply it to 19 | your programs, too. 20 | 21 | When we speak of free software, we are referring to freedom, not 22 | price. Our General Public Licenses are designed to make sure that you 23 | have the freedom to distribute copies of free software (and charge for 24 | this service if you wish), that you receive source code or can get it 25 | if you want it, that you can change the software or use pieces of it 26 | in new free programs; and that you know you can do these things. 27 | 28 | To protect your rights, we need to make restrictions that forbid 29 | anyone to deny you these rights or to ask you to surrender the rights. 30 | These restrictions translate to certain responsibilities for you if you 31 | distribute copies of the software, or if you modify it. 32 | 33 | For example, if you distribute copies of such a program, whether 34 | gratis or for a fee, you must give the recipients all the rights that 35 | you have. You must make sure that they, too, receive or can get the 36 | source code. And you must show them these terms so they know their 37 | rights. 38 | 39 | We protect your rights with two steps: (1) copyright the software, and 40 | (2) offer you this license which gives you legal permission to copy, 41 | distribute and/or modify the software. 42 | 43 | Also, for each author's protection and ours, we want to make certain 44 | that everyone understands that there is no warranty for this free 45 | software. If the software is modified by someone else and passed on, we 46 | want its recipients to know that what they have is not the original, so 47 | that any problems introduced by others will not reflect on the original 48 | authors' reputations. 49 | 50 | Finally, any free program is threatened constantly by software 51 | patents. We wish to avoid the danger that redistributors of a free 52 | program will individually obtain patent licenses, in effect making the 53 | program proprietary. To prevent this, we have made it clear that any 54 | patent must be licensed for everyone's free use or not licensed at all. 55 | 56 | The precise terms and conditions for copying, distribution and 57 | modification follow. 58 | 59 | GNU GENERAL PUBLIC LICENSE 60 | TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION 61 | 62 | 0. This License applies to any program or other work which contains 63 | a notice placed by the copyright holder saying it may be distributed 64 | under the terms of this General Public License. The "Program", below, 65 | refers to any such program or work, and a "work based on the Program" 66 | means either the Program or any derivative work under copyright law: 67 | that is to say, a work containing the Program or a portion of it, 68 | either verbatim or with modifications and/or translated into another 69 | language. (Hereinafter, translation is included without limitation in 70 | the term "modification".) Each licensee is addressed as "you". 71 | 72 | Activities other than copying, distribution and modification are not 73 | covered by this License; they are outside its scope. The act of 74 | running the Program is not restricted, and the output from the Program 75 | is covered only if its contents constitute a work based on the 76 | Program (independent of having been made by running the Program). 77 | Whether that is true depends on what the Program does. 78 | 79 | 1. You may copy and distribute verbatim copies of the Program's 80 | source code as you receive it, in any medium, provided that you 81 | conspicuously and appropriately publish on each copy an appropriate 82 | copyright notice and disclaimer of warranty; keep intact all the 83 | notices that refer to this License and to the absence of any warranty; 84 | and give any other recipients of the Program a copy of this License 85 | along with the Program. 86 | 87 | You may charge a fee for the physical act of transferring a copy, and 88 | you may at your option offer warranty protection in exchange for a fee. 89 | 90 | 2. You may modify your copy or copies of the Program or any portion 91 | of it, thus forming a work based on the Program, and copy and 92 | distribute such modifications or work under the terms of Section 1 93 | above, provided that you also meet all of these conditions: 94 | 95 | a) You must cause the modified files to carry prominent notices 96 | stating that you changed the files and the date of any change. 97 | 98 | b) You must cause any work that you distribute or publish, that in 99 | whole or in part contains or is derived from the Program or any 100 | part thereof, to be licensed as a whole at no charge to all third 101 | parties under the terms of this License. 102 | 103 | c) If the modified program normally reads commands interactively 104 | when run, you must cause it, when started running for such 105 | interactive use in the most ordinary way, to print or display an 106 | announcement including an appropriate copyright notice and a 107 | notice that there is no warranty (or else, saying that you provide 108 | a warranty) and that users may redistribute the program under 109 | these conditions, and telling the user how to view a copy of this 110 | License. (Exception: if the Program itself is interactive but 111 | does not normally print such an announcement, your work based on 112 | the Program is not required to print an announcement.) 113 | 114 | These requirements apply to the modified work as a whole. If 115 | identifiable sections of that work are not derived from the Program, 116 | and can be reasonably considered independent and separate works in 117 | themselves, then this License, and its terms, do not apply to those 118 | sections when you distribute them as separate works. But when you 119 | distribute the same sections as part of a whole which is a work based 120 | on the Program, the distribution of the whole must be on the terms of 121 | this License, whose permissions for other licensees extend to the 122 | entire whole, and thus to each and every part regardless of who wrote it. 123 | 124 | Thus, it is not the intent of this section to claim rights or contest 125 | your rights to work written entirely by you; rather, the intent is to 126 | exercise the right to control the distribution of derivative or 127 | collective works based on the Program. 128 | 129 | In addition, mere aggregation of another work not based on the Program 130 | with the Program (or with a work based on the Program) on a volume of 131 | a storage or distribution medium does not bring the other work under 132 | the scope of this License. 133 | 134 | 3. You may copy and distribute the Program (or a work based on it, 135 | under Section 2) in object code or executable form under the terms of 136 | Sections 1 and 2 above provided that you also do one of the following: 137 | 138 | a) Accompany it with the complete corresponding machine-readable 139 | source code, which must be distributed under the terms of Sections 140 | 1 and 2 above on a medium customarily used for software interchange; or, 141 | 142 | b) Accompany it with a written offer, valid for at least three 143 | years, to give any third party, for a charge no more than your 144 | cost of physically performing source distribution, a complete 145 | machine-readable copy of the corresponding source code, to be 146 | distributed under the terms of Sections 1 and 2 above on a medium 147 | customarily used for software interchange; or, 148 | 149 | c) Accompany it with the information you received as to the offer 150 | to distribute corresponding source code. (This alternative is 151 | allowed only for noncommercial distribution and only if you 152 | received the program in object code or executable form with such 153 | an offer, in accord with Subsection b above.) 154 | 155 | The source code for a work means the preferred form of the work for 156 | making modifications to it. For an executable work, complete source 157 | code means all the source code for all modules it contains, plus any 158 | associated interface definition files, plus the scripts used to 159 | control compilation and installation of the executable. However, as a 160 | special exception, the source code distributed need not include 161 | anything that is normally distributed (in either source or binary 162 | form) with the major components (compiler, kernel, and so on) of the 163 | operating system on which the executable runs, unless that component 164 | itself accompanies the executable. 165 | 166 | If distribution of executable or object code is made by offering 167 | access to copy from a designated place, then offering equivalent 168 | access to copy the source code from the same place counts as 169 | distribution of the source code, even though third parties are not 170 | compelled to copy the source along with the object code. 171 | 172 | 4. You may not copy, modify, sublicense, or distribute the Program 173 | except as expressly provided under this License. Any attempt 174 | otherwise to copy, modify, sublicense or distribute the Program is 175 | void, and will automatically terminate your rights under this License. 176 | However, parties who have received copies, or rights, from you under 177 | this License will not have their licenses terminated so long as such 178 | parties remain in full compliance. 179 | 180 | 5. You are not required to accept this License, since you have not 181 | signed it. However, nothing else grants you permission to modify or 182 | distribute the Program or its derivative works. These actions are 183 | prohibited by law if you do not accept this License. Therefore, by 184 | modifying or distributing the Program (or any work based on the 185 | Program), you indicate your acceptance of this License to do so, and 186 | all its terms and conditions for copying, distributing or modifying 187 | the Program or works based on it. 188 | 189 | 6. Each time you redistribute the Program (or any work based on the 190 | Program), the recipient automatically receives a license from the 191 | original licensor to copy, distribute or modify the Program subject to 192 | these terms and conditions. You may not impose any further 193 | restrictions on the recipients' exercise of the rights granted herein. 194 | You are not responsible for enforcing compliance by third parties to 195 | this License. 196 | 197 | 7. If, as a consequence of a court judgment or allegation of patent 198 | infringement or for any other reason (not limited to patent issues), 199 | conditions are imposed on you (whether by court order, agreement or 200 | otherwise) that contradict the conditions of this License, they do not 201 | excuse you from the conditions of this License. If you cannot 202 | distribute so as to satisfy simultaneously your obligations under this 203 | License and any other pertinent obligations, then as a consequence you 204 | may not distribute the Program at all. For example, if a patent 205 | license would not permit royalty-free redistribution of the Program by 206 | all those who receive copies directly or indirectly through you, then 207 | the only way you could satisfy both it and this License would be to 208 | refrain entirely from distribution of the Program. 209 | 210 | If any portion of this section is held invalid or unenforceable under 211 | any particular circumstance, the balance of the section is intended to 212 | apply and the section as a whole is intended to apply in other 213 | circumstances. 214 | 215 | It is not the purpose of this section to induce you to infringe any 216 | patents or other property right claims or to contest validity of any 217 | such claims; this section has the sole purpose of protecting the 218 | integrity of the free software distribution system, which is 219 | implemented by public license practices. Many people have made 220 | generous contributions to the wide range of software distributed 221 | through that system in reliance on consistent application of that 222 | system; it is up to the author/donor to decide if he or she is willing 223 | to distribute software through any other system and a licensee cannot 224 | impose that choice. 225 | 226 | This section is intended to make thoroughly clear what is believed to 227 | be a consequence of the rest of this License. 228 | 229 | 8. If the distribution and/or use of the Program is restricted in 230 | certain countries either by patents or by copyrighted interfaces, the 231 | original copyright holder who places the Program under this License 232 | may add an explicit geographical distribution limitation excluding 233 | those countries, so that distribution is permitted only in or among 234 | countries not thus excluded. In such case, this License incorporates 235 | the limitation as if written in the body of this License. 236 | 237 | 9. The Free Software Foundation may publish revised and/or new versions 238 | of the General Public License from time to time. Such new versions will 239 | be similar in spirit to the present version, but may differ in detail to 240 | address new problems or concerns. 241 | 242 | Each version is given a distinguishing version number. If the Program 243 | specifies a version number of this License which applies to it and "any 244 | later version", you have the option of following the terms and conditions 245 | either of that version or of any later version published by the Free 246 | Software Foundation. If the Program does not specify a version number of 247 | this License, you may choose any version ever published by the Free Software 248 | Foundation. 249 | 250 | 10. If you wish to incorporate parts of the Program into other free 251 | programs whose distribution conditions are different, write to the author 252 | to ask for permission. For software which is copyrighted by the Free 253 | Software Foundation, write to the Free Software Foundation; we sometimes 254 | make exceptions for this. Our decision will be guided by the two goals 255 | of preserving the free status of all derivatives of our free software and 256 | of promoting the sharing and reuse of software generally. 257 | 258 | NO WARRANTY 259 | 260 | 11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY 261 | FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN 262 | OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES 263 | PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED 264 | OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 265 | MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS 266 | TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE 267 | PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, 268 | REPAIR OR CORRECTION. 269 | 270 | 12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING 271 | WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR 272 | REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, 273 | INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING 274 | OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED 275 | TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY 276 | YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER 277 | PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE 278 | POSSIBILITY OF SUCH DAMAGES. 279 | 280 | END OF TERMS AND CONDITIONS 281 | 282 | How to Apply These Terms to Your New Programs 283 | 284 | If you develop a new program, and you want it to be of the greatest 285 | possible use to the public, the best way to achieve this is to make it 286 | free software which everyone can redistribute and change under these terms. 287 | 288 | To do so, attach the following notices to the program. It is safest 289 | to attach them to the start of each source file to most effectively 290 | convey the exclusion of warranty; and each file should have at least 291 | the "copyright" line and a pointer to where the full notice is found. 292 | 293 | 294 | Copyright (C) 295 | 296 | This program is free software; you can redistribute it and/or modify 297 | it under the terms of the GNU General Public License as published by 298 | the Free Software Foundation; either version 2 of the License, or 299 | (at your option) any later version. 300 | 301 | This program is distributed in the hope that it will be useful, 302 | but WITHOUT ANY WARRANTY; without even the implied warranty of 303 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 304 | GNU General Public License for more details. 305 | 306 | You should have received a copy of the GNU General Public License along 307 | with this program; if not, see . 308 | 309 | Also add information on how to contact you by electronic and paper mail. 310 | 311 | If the program is interactive, make it output a short notice like this 312 | when it starts in an interactive mode: 313 | 314 | Gnomovision version 69, Copyright (C) year name of author 315 | Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'. 316 | This is free software, and you are welcome to redistribute it 317 | under certain conditions; type `show c' for details. 318 | 319 | The hypothetical commands `show w' and `show c' should show the appropriate 320 | parts of the General Public License. Of course, the commands you use may 321 | be called something other than `show w' and `show c'; they could even be 322 | mouse-clicks or menu items--whatever suits your program. 323 | 324 | You should also get your employer (if you work as a programmer) or your 325 | school, if any, to sign a "copyright disclaimer" for the program, if 326 | necessary. Here is a sample; alter the names: 327 | 328 | Yoyodyne, Inc., hereby disclaims all copyright interest in the program 329 | `Gnomovision' (which makes passes at compilers) written by James Hacker. 330 | 331 | , 1 April 1989 332 | Moe Ghoul, President of Vice 333 | 334 | This General Public License does not permit incorporating your program into 335 | proprietary programs. If your program is a subroutine library, you may 336 | consider it more useful to permit linking proprietary applications with the 337 | library. If this is what you want to do, use the GNU Lesser General 338 | Public License instead of this License. 339 | --------------------------------------------------------------------------------