74 lines
3.9 KiB
HTML
74 lines
3.9 KiB
HTML
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<title>Description of qbeta</title>
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<meta name="description" content="QBETA The beta inverse distribution function">
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<div><a href="../index.html">Home</a> > <a href="index.html">.</a> > qbeta.m</div>
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<!--<table width="100%"><tr><td align="left"><a href="../index.html"><img alt="<" border="0" src="../left.png"> Master index</a></td>
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<td align="right"><a href="index.html">Index for . <img alt=">" border="0" src="../right.png"></a></td></tr></table>-->
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<h1>qbeta
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</h1>
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<h2><a name="_name"></a>PURPOSE <a href="#_top"><img alt="^" border="0" src="../up.png"></a></h2>
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<div class="box"><strong>QBETA The beta inverse distribution function</strong></div>
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<h2><a name="_synopsis"></a>SYNOPSIS <a href="#_top"><img alt="^" border="0" src="../up.png"></a></h2>
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<div class="box"><strong>function x = qbeta(p,a,b) </strong></div>
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<h2><a name="_description"></a>DESCRIPTION <a href="#_top"><img alt="^" border="0" src="../up.png"></a></h2>
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<div class="fragment"><pre class="comment">QBETA The beta inverse distribution function
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x = qbeta(p,a,b)</pre></div>
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<!-- crossreference -->
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<h2><a name="_cross"></a>CROSS-REFERENCE INFORMATION <a href="#_top"><img alt="^" border="0" src="../up.png"></a></h2>
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This function calls:
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<ul style="list-style-image:url(../matlabicon.gif)">
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<li><a href="dbeta.html" class="code" title="function d = dbeta(x,a,b)">dbeta</a> DBETA The beta density function</li></ul>
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This function is called by:
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<ul style="list-style-image:url(../matlabicon.gif)">
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<li><a href="compDist.html" class="code" title="function compdist(xparam1, x2, pltopt, figurename)">compDist</a> </li><li><a href="draw_prior_density.html" class="code" title="function [x,f,abscissa,dens,binf,bsup] = draw_prior_density(indx);">draw_prior_density</a> stephane.adjemian@ens.fr [07-15-2004]</li><li><a href="prior_bounds.html" class="code" title="function bounds = prior_bounds(bayestopt)">prior_bounds</a> </li></ul>
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<!-- crossreference -->
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<h2><a name="_source"></a>SOURCE CODE <a href="#_top"><img alt="^" border="0" src="../up.png"></a></h2>
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<div class="fragment"><pre>0001 <a name="_sub0" href="#_subfunctions" class="code">function x = qbeta(p,a,b)</a>
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0002 <span class="comment">%QBETA The beta inverse distribution function</span>
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0003 <span class="comment">%</span>
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0004 <span class="comment">% x = qbeta(p,a,b)</span>
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0005
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0006 <span class="comment">% Anders Holtsberg, 27-07-95</span>
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0007 <span class="comment">% Copyright (c) Anders Holtsberg</span>
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0008
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0009 <span class="keyword">if</span> any(any((a<=0)|(b<=0)))
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0010 error(<span class="string">'Parameter a or b is nonpositive'</span>)
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0011 <span class="keyword">end</span>
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0012 <span class="keyword">if</span> any(any(abs(2*p-1)>1))
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0013 error(<span class="string">'A probability should be 0<=p<=1, please!'</span>)
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0014 <span class="keyword">end</span>
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0015 b = min(b,100000);
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0016
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0017 x = a ./ (a+b);
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0018 dx = 1;
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0019 <span class="keyword">while</span> any(any(abs(dx)>256*eps*max(x,1)))
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0020 dx = (betainc(x,a,b) - p) ./ <a href="dbeta.html" class="code" title="function d = dbeta(x,a,b)">dbeta</a>(x,a,b);
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0021 x = x - dx;
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0022 x = x + (dx - x) / 2 .* (x<0);
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0023 x = x + (1 + (dx - x)) / 2 .* (x>1);
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0024 <span class="keyword">end</span>
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0025
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0026</pre></div>
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<hr><address>Generated on Fri 16-Jun-2006 09:09:06 by <strong><a href="http://www.artefact.tk/software/matlab/m2html/">m2html</a></strong> © 2003</address>
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