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EventStatistics.php @ 1

Last change on this file since 1 was 1, checked in by zerwas, 11 years ago
first import of structure, PYTHIA8 and DELPHES
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1	<html>
2	<head>
3	<title>Event Statistics</title>
4	<link rel="stylesheet" type="text/css" href="pythia.css"/>
5	<link rel="shortcut icon" href="pythia32.gif"/>
6	</head>
7	<body>
8
9	<script language=javascript type=text/javascript>
10	function stopRKey(evt) {
11	var evt = (evt) ? evt : ((event) ? event : null);
12	var node = (evt.target) ? evt.target :((evt.srcElement) ? evt.srcElement : null);
13	if ((evt.keyCode == 13) && (node.type=="text"))
14	{return false;}
15	}
16
17	document.onkeypress = stopRKey;
18	</script>
19	<?php
20	if($_POST['saved'] == 1) {
21	if($_POST['filepath'] != "files/") {
22	echo "<font color='red'>SETTINGS SAVED TO FILE</font><br/><br/>"; }
23	else {
24	echo "<font color='red'>NO FILE SELECTED YET.. PLEASE DO SO </font><a href='SaveSettings.php'>HERE</a><br/><br/>"; }
25	}
26	?>
27
28	<form method='post' action='EventStatistics.php'>
29
30	<h2>Event Statistics</h2>
31
32	At the end of the run you will want to write out the final statistics
33	on number of events generated, the corresponding cross sections and
34	the number of errors encountered. This is done either with the
35	<code>pythia.stat()</code> method or the <code>pythia.statistics()</code>
36	one, assuming <code>pythia</code> is an instance of the
37	<code>Pythia</code> class.The former method is steered entirely by
38	settings values, see <?php $filepath = $_GET["filepath"];
39	echo "<a href='MainProgramSettings.php?filepath=".$filepath."' target='page'>";?>here</a>.
40	The latter, deprecated one instead takes two arguments:
41
42	<a name="method1"></a>
43	<p/><strong>void Pythia::statistics(bool all = false, bool reset = false)  </strong> <br/>
44	write out statistics on cross sections and errors. This is based on
45	calls to the methods below, for the two kinds of information.
46	<br/><code>argument</code><strong> all </strong> :
47	if <code>true</code> it allows a more extensive listing than the default
48	one, see multiparton-interactions statistics below.
49
50	<br/><code>argument</code><strong> reset </strong> : if <code>true</code> it implies that all counters,
51	e.g on events generated and errors experienced, are reset to zero whenever
52	the routine is called. The default instead is that all stored
53	statistics information is unaffected by the call.
54	Counters are automatically reset in each new <code>Pythia::init()</code>
55	call, however, so the only time the <code>reset</code> option makes a
56	difference is if <code>statistics(...)</code> is called several times
57	in a (sub)run.
58
59
60
61	<h3>Cross-section statistics</h3>
62
63	The <code>ProcessLevel::statistics()</code> method cannot be accessed
64	directly, but only via the <code>Pythia::stat()</code> and
65	<code>Pythia::statistics(...)</code> calls above.
66	When called it will loop over the list of existing processes, and for
67	each write out name, code, the number of tried, selected and accepted
68	events, the cross section and the estimated error on the latter.
69	The three different event numbers are related to the Monte Carlo method
70	used, whereby an initial upper estimate of the cross section is used to
71	select a large number of trial phase-space points, whereof then not all
72	survive. Rejections are normally done by the internal machinery, but can
73	also be obtained by <?php $filepath = $_GET["filepath"];
74	echo "<a href='UserHooks.php?filepath=".$filepath."' target='page'>";?>user hooks</a>.
75	Therefore:
76	<ul>
77	<li><b>tried</b> events reflect the original number of
78	phase-space points probed, as part of the upper estimate;</li>
79	<li><b>selected</b> events correspond to those that survive
80	the internal Monte-Carlo selection procedure;</li>
81	<li><b>accepted</b> events are those that also survive
82	the additional user cuts.</li>
83	</ul>
84	In most runs there would be no user hooks implemented, and then the
85	numbers of selected and of accepted events will agree. Aborted events
86	(see below) usually appear in the selected statistics but not in the
87	accepted one.
88
89	<p/>
90	For Les Houches events the total cross section will be correctly
91	displayed; however the (optional) error value will not be used, so that
92	the reported error will be smaller than the correct statistical ones,
93	and often vanish completely. Furthermore, while the number of events
94	is shown for each user process, the cross section is only for the sum
95	of them.
96
97	<h3>Error messages</h3>
98
99	When Pythia is run, errors may occur, and give rise to warning messages.
100	These may be of varying severity, as follows:
101	<ul>
102	<li><b>Abort</b> means things went seriously wrong, and the
103	initialization or event generation failed. In the former case it is
104	not possible to generate events at all, in the latter the current
105	event is flawed and should be skipped. In either case the respective
106	method, <code>Pythia::init()</code> or <code>Pythia::next()</code>,
107	then also returns the value <code>false</code>. There are occasions
108	where an abort may be deliberate, such as when a file of Les Houches
109	Events is read and the end of the file is reached.</li>
110	<li><b>Error</b> normally is less severe. Typically the program will
111	back up one step and try again. There are cases where this is not possible,
112	in particular during the initialization and the generation of a hard
113	process, and then the error may be followed by an abort as a direct
114	consequence (with two separate messages).</li>
115	<li><b>Warning</b> is even less severe. In some cases the program will
116	try again, with good chances of success, in others no measure at all
117	need to be taken.</li>
118	</ul>
119
120	<p/>
121	The error messages is handled by a small part of the <code>Info</code>
122	class. It is handed any abort, error or warning messages during the event
123	generation phase, and will store each distinct message, with a counter
124	for how many times it is issued. Thus it is possible to limit the number
125	of identical messages issued, currently hardcoded so that each kind of
126	error message is only printed once
127	(<code>static const int TIMESTOPRINT = 1</code>).
128	This can be overridden by the calling routine, so that all messages of
129	this kind are shown, which is particularly relevant for the
130	initialization stage.
131	The summary table printed by <code>Pythia::statistics()</code>
132	provides a table with all the different messages issued, in
133	alphabetical order, with the total number of times each was generated.
134
135	<h3>Multiparton-interactions statistics</h3>
136
137	If you call <code>Pythia::statistics(true)</code>, i.e. with the first
138	optional argument <code>true</code>, also statistics on multiparton
139	interactions is printed, comprising a list of all allowed subprocesses
140	with how many times each of them has been generated. For the minimum-bias
141	process this also includes the hardest interaction, while else the
142	hardest process is excluded from the statistics. (This is because
143	the hardest process is of the same character and generated by the same
144	machinery in the former case but not in the latter. Also, for the
145	former case only, the standard statistics listing only lists
146	minimum bias as one single process, i.e. does not further specify
147	the character of the hardest subprocess, so there is not any overlap
148	between the two.)
149
150	</body>
151	</html>
152
153	<!-- Copyright (C) 2012 Torbjorn Sjostrand -->

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