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<title>Qhull print options (P)</title>
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<body>
<!-- Navigation links -->
<p><b>Up:</b> <a href="http://www.geom.umn.edu/locate/qhull">Home page</a> for Qhull<br>
<b>Up:</b> <a href="index.htm#TOC">Qhull manual</a>: Table of Contents<br>
<b>To:</b> <a href="qh-quick.htm#programs">Programs</a>
&#149;</a> <a href="qh-quick.htm#options">Options</a>
&#149; <a href="qh-opto.htm#output">Output</a>
&#149; <a href="qh-optf.htm#format">Formats</a>
&#149; <a href="qh-optg.htm#geomview">Geomview</a>
&#149; <a href="qh-optp.htm#print">Print</a>
&#149; <a href="qh-optq.htm#qhull">Qhull</a>
&#149; <a href="qh-optc.htm#prec">Precision</a>
&#149; <a href="qh-optt.htm#trace">Trace</a></p>
<hr>
<!-- Main text of document -->
<h1><a
href="http://www.geom.umn.edu/graphics/pix/Special_Topics/Computational_Geometry/delaunay.html"><img
src="qh--dt.gif" alt="[delaunay]" align="middle" width="100"
height="100"></a> Qhull print options (P)</h1>
This section lists the print options for Qhull. These options are
indicated by 'P' followed by a letter. See
<a href="qh-opto.htm#output">Output</a>, <a href="qh-optg.htm#geomview">Geomview</a>,
and <a href="qh-optf.htm#format">Format</a> for other output options.
<p><b>Copyright ｩ 1995-2001 The Geometry Center, Minneapolis MN</b></p>
<hr>
<p><a href="index.htm#TOC">ｻ</a> <a href="qh-quick.htm#programs">Programs</a>
<a name="print">&#149;</a> <a href="qh-quick.htm#options">Options</a> &#149; <a
href="qh-opto.htm#output">Output</a> &#149; <a
href="qh-optf.htm#format">Formats</a> &#149; <a
href="qh-optg.htm#geomview">Geomview</a> &#149; <a href="#print">Print</a>
&#149; <a href="qh-optq.htm#qhull">Qhull</a> &#149; <a
href="qh-optc.htm#prec">Precision</a> &#149; <a
href="qh-optt.htm#trace">Trace</a></p>
<h2>Print options</h2>
<blockquote>
<dl compact>
<dt>&nbsp;</dt>
<dd><b>General</b></dd>
<dt><a href="#Pp">Pp</a></dt>
<dd>do not report precision problems </dd>
<dt><a href="#Po">Po</a></dt>
<dd>force output despite precision problems</dd>
<dt><a href="#Po2">Po</a></dt>
<dd>if error, output neighborhood of facet</dd>
<dt>&nbsp;</dt>
<dt>&nbsp;</dt>
<dd><b>Select</b></dd>
<dt><a href="#Pdk">Pdk:n</a></dt>
<dd>print facets with normal[k] &gt;= n (default 0.0)</dd>
<dt><a href="#PDk">PDk:n</a></dt>
<dd>print facets with normal[k] &lt;= n </dd>
<dt><a href="#PFn">PFn</a></dt>
<dd>print facets whose area is at least n</dd>
<dt><a href="#Pg">Pg</a></dt>
<dd>print good facets only (needs '<a href="qh-optq.htm#QGn">QGn</a>'
or '<a href="qh-optq.htm#QVn">QVn </a>')</dd>
<dt><a href="#PMn">PMn</a></dt>
<dd>print n facets with most merges</dd>
<dt><a href="#PAn">PAn</a></dt>
<dd>print n largest facets by area</dd>
<dt><a href="#PG">PG</a></dt>
<dd>print neighbors of good facets</dd>
</dl>
</blockquote>
<hr>
<h3><a href="#print">ｻ</a><a name="PAn">PAn - keep n largest
facets by area</a></h3>
<p>The <i>n</i> largest facets are marked good for printing. This
may be useful for <a href="qh-impre.htm#approximate">approximating
a hull</a>. Unless '<a href="#PG">PG</a>' is set, '<a href="#Pg">Pg</a>'
is automatically set. </p>
<h3><a href="#print">ｻ</a><a name="Pdk">Pdk:n - print facet if
normal[k] &gt;= n </a></h3>
<p>For a given output, print only those facets with <i>normal[k] &gt;= n</i>
and <i>drop</i> the others. For example, 'Pd0:0.5' prints facets with <i>normal[0]
&gt;= 0.5 </i>. The default value of <i>n</i> is zero. For
example in 3-d, 'Pd0d1d2' prints facets in the positive octant.
<p>
If no facets match, the closest facet is returned.</p>
<p>
On Windows 95, do not combine multiple options. A 'd' is considered
part of a number. For example, use 'Pd0:0.5 Pd1:0.5' instead of
'Pd0:0.5d1:0.5'.
<h3><a href="#print">ｻ</a><a name="PDk">PDk:n - print facet if
normal[k] &lt;= n</a></h3>
<p>For a given output, print only those facets with <i>normal[k] &lt;= n</i>
and <i>drop</i> the others.
For example, 'PD0:0.5' prints facets with <i>normal[0]
&lt;= 0.5 </i>. The default value of <i>n</i> is zero. For
example in 3-d, 'PD0D1D2' displays facets in the negative octant.
<p>
If no facets match, the closest facet is returned.</p>
<p>In 2-d, 'd G PD2' displays the Delaunay triangulation instead
of the corresponding paraboloid. </p>
<p>Be careful of placing 'Dk' or 'dk' immediately after a real
number. Some compilers treat the 'D' as a double precision
exponent. </p>
<h3><a href="#print">ｻ</a><a name="PFn">PFn - keep facets whose
area is at least n</a></h3>
<p>The facets with area at least <i>n</i> are marked good for
printing. This may be useful for <a
href="qh-impre.htm#approximate">approximating a hull</a>. Unless
'<a href="#PG">PG</a>' is set, '<a href="#Pg">Pg</a>' is
automatically set. </p>
<h3><a href="#print">ｻ</a><a name="Pg">Pg - print good facets </a></h3>
<p>Qhull can mark facets as &quot;good&quot;. This is used to</p>
<ul>
<li>mark the lower convex hull for Delaunay triangulations
and Voronoi diagrams</li>
<li>mark the facets that are visible from a point (the '<a
href="qh-optq.htm#QGn">QGn </a>' option)</li>
<li>mark the facets that contain a point (the '<a
href="qh-optq.htm#QVn">QVn</a>' option).</li>
<li>indicate facets with a large enough area (options '<a
href="#PAn">PAn</a>' and '<a href="#PFn">PFn</a>')</li>
</ul>
<p>Option '<a href="#Pg">Pg</a>' only prints good facets that
also meet '<a href="#Pdk">Pdk</a>' and '<a href="#PDk">PDk</a>'
options. It is automatically set for options '<a href="#PAn">PAn</a>',
'<a href="#PFn">PFn </a>', '<a href="qh-optq.htm#QGn">QGn</a>',
and '<a href="qh-optq.htm#QVn">QVn</a>'.</p>
<h3><a href="#print">ｻ</a><a name="PG">PG - print neighbors of
good facets</a></h3>
<p>Option 'PG' can be used with or without option '<a href="#Pg">Pg</a>'
to print the neighbors of good facets. For example, options '<a
href="qh-optq.htm#QGn">QGn</a>' and '<a href="qh-optq.htm#QVn">QVn</a>'
print the horizon facets for point <i>n. </i></p>
<h3><a href="#print">ｻ</a><a name="PMn">PMn - keep n facets with
most merges</a></h3>
<p>The n facets with the most merges are marked good for
printing. This may be useful for <a
href="qh-impre.htm#approximate">approximating a hull</a>. Unless
'<a href="#PG">PG</a>' is set, '<a href="#Pg">Pg</a>' is
automatically set. </p>
<h3><a href="#print">ｻ</a><a name="Po">Po - force output despite
precision problems</a></h3>
<p>Use options 'Po' and '<a href="qh-optq.htm#Q0">Q0</a>' if you
can not merge facets or use joggled input.
Option 'Po' can not force output when
duplicate ridges or duplicate facets occur. It may produce
erroneous results. For these reasons, merged facets, joggled input, or <a
href="qh-impre.htm#exact">exact arithmetic</a> are better.</p>
<p>If you need a simplicial Delaunay triangulation, use
joggled input '<a href="qh-optq.htm#QJn">QJ</a>' or triangulated
output '<a
href="qh-optf.htm#Ft">Ft</a>'.
<p>Option 'Po' may be used without '<a href="qh-optq.htm#Q0">Q0</a>'
to remove some steps from Qhull or to output the neighborhood of
an error.</p>
<p>If option 'Po' is used,</p>
<ul>
<li>most precision errors allow Qhull to continue. </li>
<li>the maximum outside distance is not determined
(qh_check_maxout and option '<a href="qh-optq.htm#Q5">Q5</a>').
This can save a significant amount of time.</li>
<li>verify ('<a href="qh-optt.htm#Tv">Tv</a>') does not check
coplanar points.</li>
<li>points are not partitioned into flipped facets and a
flipped facet is always visible to a point. This may
delete flipped facets from the output. </li>
</ul>
<h3><a href="#print">ｻ</a><a name="Po2">Po - if error, output
neighborhood of facet</a></h3>
<p>If an error occurs before the completion of Qhull and tracing
is not active, 'Po' outputs a neighborhood of the erroneous
facets (if any). It uses the current output options.</p>
<h3><a href="#print">ｻ</a><a name="Pp">Pp - do not report
precision problems </a></h3>
<p>With option 'Pp', Qhull does not print statistics about
precision problems, and it removes some of the warnings. It
removes the narrow hull warning.</p>
<!-- Navigation links -->
<hr>
<p><b>Up:</b> <a href="http://www.geom.umn.edu/locate/qhull">Home page</a> for Qhull<br>
<b>Up:</b> <a href="index.htm#TOC">Qhull manual</a>: Table of Contents<br>
<b>To:</b> <a href="qh-quick.htm#programs">Programs</a>
&#149;</a> <a href="qh-quick.htm#options">Options</a>
&#149; <a href="qh-opto.htm#output">Output</a>
&#149; <a href="qh-optf.htm#format">Formats</a>
&#149; <a href="qh-optg.htm#geomview">Geomview</a>
&#149; <a href="qh-optp.htm#print">Print</a>
&#149; <a href="qh-optq.htm#qhull">Qhull</a>
&#149; <a href="qh-optc.htm#prec">Precision</a>
&#149; <a href="qh-optt.htm#trace">Trace</a></p>
<!-- GC common information -->
<hr>
<p><a href="http://www.geom.umn.edu/"><img src="qh--geom.gif"
align="middle" width="40" height="40"></a><i>The Geometry Center
Home Page </i></p>
<p>Comments to: <a
href="http://www.geom.umn.edu/software/qhull/qhull-mail.html">qhull@geom.umn.edu
</a><br>
Created: Sept. 25, 1995 --- <!-- hhmts start --> Last modified: see top <!-- hhmts end --> </p>
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