279 lines
11 KiB
HTML
279 lines
11 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML//EN">
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<title>Qhull trace options (T)</title>
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</head>
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<body>
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<!-- Navigation links -->
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<p><b>Up:</b> <a href="http://www.qhull.org">Home page</a> for Qhull<br>
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<b>Up:</b> <a href="index.htm#TOC">Qhull manual</a>: Table of Contents<br>
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<b>To:</b> <a href="qh-quick.htm#programs">Programs</a>
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• <a href="qh-quick.htm#options">Options</a>
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• <a href="qh-opto.htm#output">Output</a>
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• <a href="qh-optf.htm#format">Formats</a>
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• <a href="qh-optg.htm#geomview">Geomview</a>
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• <a href="qh-optp.htm#print">Print</a>
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• <a href="qh-optq.htm#qhull">Qhull</a>
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• <a href="qh-optc.htm#prec">Precision</a>
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• <a href="qh-optt.htm#trace">Trace</a>
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• <a href="../src/libqhull_r/index.htm">Functions</a></p>
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<hr>
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<!-- Main text of document -->
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<h1><a
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href="http://www.geom.uiuc.edu/graphics/pix/Special_Topics/Computational_Geometry/delaunay.html"><img
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src="qh--dt.gif" alt="[delaunay]" align="middle" width="100"
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height="100"></a> Qhull trace options (T)</h1>
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This section lists the trace options for Qhull. These options are
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indicated by 'T' followed by a letter.
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<p><b>Copyright © 1995-2015 C.B. Barber</b></p>
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<hr>
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<p><a href="index.htm#TOC">»</a> <a href="qh-quick.htm#programs">Programs</a>
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<a name="trace">•</a> <a href="qh-quick.htm#options">Options</a>
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• <a href="qh-opto.htm#output">Output</a>
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• <a href="qh-optf.htm#format">Formats</a>
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• <a href="qh-optg.htm#geomview">Geomview</a>
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• <a href="qh-optp.htm#print">Print</a>
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• <a href="qh-optq.htm#qhull">Qhull</a>
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• <a href="qh-optc.htm#prec">Precision</a>
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• <a href="qh-optt.htm#trace">Trace</a>
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• <a href="../src/libqhull_r/index.htm">Functions</a></p>
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<h2>Trace options</h2>
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<dl compact>
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<dt> </dt>
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<dd><b>General</b></dd>
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<dt><a href="#Tz">Tz</a></dt>
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<dd>output error information to stdout instead of stderr</dd>
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<dt><a href="#TI">TI file</a></dt>
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<dd>input data from a file</dd>
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<dt><a href="#TO">TO file</a></dt>
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<dd>output results to a file</dd>
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<dt><a href="#Ts">Ts</a></dt>
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<dd>print statistics</dd>
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<dt><a href="#TFn">TFn</a></dt>
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<dd>report progress whenever n or more facets created</dd>
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<dt><a href="#TRn">TRn</a></dt>
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<dd>rerun qhull n times</dd>
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<dt><a href="#Tv">Tv</a></dt>
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<dd>verify result: structure, convexity, and point inclusion</dd>
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<dt> </dt>
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<dt> </dt>
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<dd><b>Debugging</b></dd>
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<dt><a href="#Tc">Tc</a></dt>
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<dd>check frequently during execution</dd>
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<dt><a href="#TVn2">TVn</a></dt>
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<dd>stop qhull after adding point n </dd>
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<dt><a href="#TCn">TCn</a></dt>
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<dd>stop qhull after building cone for point n</dd>
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<dt><a href="#TVn">TV-n</a></dt>
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<dd>stop qhull before adding point n</dd>
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<dt><a href="#Tn">T4</a></dt>
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<dd>trace at level n, 4=all, 5=mem/gauss, -1= events</dd>
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<dt><a href="#TWn">TWn</a></dt>
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<dd>trace merge facets when width > n</dd>
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<dt><a href="#TMn">TMn</a></dt>
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<dd>turn on tracing at merge n</dd>
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<dt><a href="#TPn">TPn</a></dt>
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<dd>turn on tracing when point n added to hull</dd>
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</dl>
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<hr>
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<h3><a href="#trace">»</a><a name="Tc">Tc - check frequently
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during execution </a></h3>
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<p>Qhull includes frequent checks of its data structures. Option
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'Tc' will catch most inconsistency errors. It is slow and should
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not be used for production runs. Option '<a href="#Tv">Tv</a>'
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performs the same checks after the hull is constructed.</p>
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<h3><a href="#trace">»</a><a name="TCn">TCn - stop qhull after
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building cone for point n</a></h3>
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<p>Qhull builds a cone from the point to its horizon facets.
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Option 'TCn' stops Qhull just after building the cone. The output
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for '<a href="qh-opto.htm#f">f</a>' includes the cone and the old
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hull.'. </p>
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<h3><a href="#trace">»</a><a name="TFn">TFn - report summary
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whenever n or more facets created </a></h3>
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<p>Option 'TFn' reports progress whenever more than n facets are
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created. The test occurs just before adding a new point to the
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hull. During post-merging, 'TFn' reports progress after more than
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<i>n/2</i> merges. </p>
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<h3><a href="#trace">»</a><a name="TI">TI file - input data from file</a></h3>
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<p>Input data from 'file' instead of stdin. The filename may not
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contain spaces or use single quotes.
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You may use I/O redirection
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instead (e.g., 'rbox 10 | qdelaunay >results').</P>
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<h3><a href="#trace">»</a><a name="TMn">TMn - turn on tracing at
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merge n </a></h3>
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<p>Turn on tracing at n'th merge. </p>
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<h3><a href="#trace">»</a><a name="Tn">Tn - trace at level n</a></h3>
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<p>Qhull includes full execution tracing. 'T-1' traces events.
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'T1' traces the overall execution of the program. 'T2' and 'T3'
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trace overall execution and geometric and topological events.
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'T4' traces the algorithm. 'T5' includes information about memory
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allocation and Gaussian elimination. 'T1' is useful for logging
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progress of Qhull in high dimensions.</p>
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<p>Option 'Tn' can produce large amounts of output. Use options '<a
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href="#TPn">TPn</a>', '<a href="#TWn">TWn</a>', and '<a href="#TMn">TMn</a>' to selectively
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turn on tracing. Since all errors report the last processed
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point, option '<a href="#TPn">TPn</a>' is particularly useful.</p>
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<p>Different executions of the same program may produce different
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traces and different results. The reason is that Qhull uses hashing
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to match ridges of non-simplicial facets. For performance reasons,
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the hash computation uses
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memory addresses which may change across executions.
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<h3><a href="#trace">»</a><a name="TO">TO file - output results to file</a></h3>
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<p>Redirect stdout to 'file'. The filename may be enclosed in
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single quotes. Unix and Windows NT users may use I/O redirection
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instead (e.g., 'rbox 10 | qdelaunay >results').</P>
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<p>
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Windows95 users should always use 'TO file'. If they use I/O redirection,
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error output is not sent to the console. Qhull uses single quotes instead
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of double quotes because a missing double quote can
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freeze Windows95 (e.g., do not run, rbox 10 | qhull TO "x)</p>
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<p>
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<h3><a href="#trace">»</a><a name="TPn">TPn - turn on tracing
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when point n added to hull </a></h3>
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<p>Option 'TPn' turns on tracing when point n is added to
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the hull. It also traces partitions of point n. This option
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reduces the output size when tracing. It is the normal
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method to determine the cause of a Qhull error. All Qhull errors
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report the last point added.
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<p>Use options 'TPn <a href="qh-optt.htm#TVn">TVn</a>' to
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trace the addition of point n to the convex hull and stop when done.</p>
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<p>If used with option '<a href="qh-optt.htm#TWn">TWn</a>',
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'TPn' turns off tracing after adding point n to the hull.
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Use options 'TPn TWn' to
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trace the addition of point n to the convex hull, partitions
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of point n, and wide merges.</p>
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<h3><a href="#trace">»</a><a name="TRn">TRn - rerun qhull n times</a></h3>
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<p>Option 'TRn' reruns Qhull n times. It is usually used
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with '<a href="qh-optq.htm#QJn">QJn</a>' to determine the probability
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that a given joggle will fail. The summary
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('<a href="qh-opto.htm#s">s</a>') lists the failure
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rate and the precision errors that occurred.
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Option '<a href="#Ts">Ts</a>' will report statistics for
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all of the runs. Trace and output options only apply to the last
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run. An event trace, '<a href="#Tn">T-1</a>' reports events for all runs.
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<p>Tracing applies to the last run of Qhull. If an error
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is reported, the options list the run number as "_run".
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To trace this run, set 'TRn' to the same value.</p>
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<h3><a href="#trace">»</a><a name="Ts">Ts - print statistics </a></h3>
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<p>Option 'Ts' collects statistics and prints them to stderr. For
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Delaunay triangulations, the angle statistics are restricted to
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the lower or upper envelope.</p>
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<h3><a href="#trace">»</a><a name="Tv">Tv - verify result:
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structure, convexity, and point inclusion </a></h3>
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<p>Option 'Tv' checks the topological structure, convexity, and
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point inclusion. If precision problems occurred, facet convexity
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is tested whether or not 'Tv' is selected. Option 'Tv' does not
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check point inclusion if forcing output with '<a
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href="qh-optp.htm#Po">Po</a>', or if '<a href="qh-optq.htm#Q5">Q5</a>'
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is set. </p>
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<p>The convex hull of a set of points is the smallest polytope
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that includes the points. Option 'Tv' tests point inclusion.
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Qhull verifies that all points are below all outer planes
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(facet->maxoutside). Point inclusion is exhaustive if merging
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or if the facet-point product is small enough; otherwise Qhull
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verifies each point with a directed search (qh_findbest). To
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force an exhaustive test when using option '<a
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href="qh-optc.htm#C0">C-0</a>' (default), use 'C-1e-30' instead. </p>
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<p>Point inclusion testing occurs after producing output. It
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prints a message to stderr unless option '<a
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href="qh-optp.htm#Pp">Pp</a>' is used. This allows the user to
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interrupt Qhull without changing the output. </p>
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<p>With '<a href=qvoronoi.htm>qvoronoi</a> <a href="qh-optf.htm#Fi2">Fi</a>'
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and '<a href=qvoronoi.htm>qvoronoi</a> <a href="qh-optf.htm#Fo2">Fo</a>',
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option 'Tv' collects statistics that verify all Voronoi vertices lie
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on the separating hyperplane, and for bounded regions, all
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separating hyperplanes are perpendicular bisectors.
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<h3><a href="#trace">»</a><a name="TVn">TV-n - stop qhull before
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adding point n</a></h3>
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<p>Qhull adds one point at a time to the convex hull. See <a
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href="qh-eg.htm#how">how Qhull adds a point</a>. Option 'TV-n'
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stops Qhull just before adding a new point. Output shows the hull
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at this time.</p>
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<h3><a href="#trace">»</a><a name="TVn2">TVn - stop qhull after
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adding point n</a></h3>
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<p>Option 'TVn' stops Qhull after it has added point n. Output
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shows the hull at this time.</p>
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<h3><a href="#trace">»</a><a name="TWn">TWn - trace merge facets
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when width > n </a></h3>
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<p>Along with TMn, this option allows the user to determine the
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cause of a wide merge.</p>
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<h3><a href="#trace">»</a><a name="Tz">Tz - send all output to
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stdout </a></h3>
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<p>Redirect stderr to stdout. </p>
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<!-- Navigation links -->
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<hr>
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<p><b>Up:</b> <a href="http://www.qhull.org">Home page</a> for Qhull<br>
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<b>Up:</b> <a href="index.htm#TOC">Qhull manual</a>: Table of Contents<br>
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<b>To:</b> <a href="qh-quick.htm#programs">Programs</a>
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• <a href="qh-quick.htm#options">Options</a>
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• <a href="qh-opto.htm#output">Output</a>
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• <a href="qh-optf.htm#format">Formats</a>
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• <a href="qh-optg.htm#geomview">Geomview</a>
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• <a href="qh-optp.htm#print">Print</a>
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• <a href="qh-optq.htm#qhull">Qhull</a>
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• <a href="qh-optc.htm#prec">Precision</a>
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• <a href="qh-optt.htm#trace">Trace</a>
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• <a href="../src/libqhull_r/index.htm">Functions</a></p>
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<!-- GC common information -->
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<hr>
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<p><a href="http://www.geom.uiuc.edu/"><img src="qh--geom.gif"
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align="middle" width="40" height="40"></a><i>The Geometry Center
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Home Page </i></p>
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<p>Comments to: <a href=mailto:qhull@qhull.org>qhull@qhull.org</a>
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</a><br>
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Created: Sept. 25, 1995 --- <!-- hhmts start --> Last modified: see top <!-- hhmts end --> </p>
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</body>
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</html>
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