<html><head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <title>invfreqs</title> <style type="text/css" media="all"> @import url("scilab_code.css"); @import url("xml_code.css"); @import url("c_code.css"); @import url("style.css"); </style> </head> <body> <div class="manualnavbar"> <table width="100%"><tr> <td width="30%"> <span class="previous"><a href="invfreq.html"><< invfreq</a></span> </td> <td width="40%" class="center"> <span class="top"><a href="section_cc2bc01c47967d47fcf3507a91d572ba.html">FOSSEE Signal Processing Toolbox</a></span> </td> <td width="30%" class="next"> <span class="next"><a href="invfreqz.html">invfreqz >></a></span> </td> </tr></table> <hr /> </div> <span class="path"><a href="index.html">FOSSEE Signal Processing Toolbox</a> >> <a href="section_cc2bc01c47967d47fcf3507a91d572ba.html">FOSSEE Signal Processing Toolbox</a> > invfreqs</span> <br /><br /> <div class="refnamediv"><h1 class="refname">invfreqs</h1> <p class="refpurpose">Fit filter B(s)/A(s)to the complex frequency response H at frequency points F. A and B are real polynomial coefficients of order nA and nB.</p></div> <div class="refsynopsisdiv"><h3 class="title">Calling Sequence</h3> <div class="synopsis"><pre><span class="default">[</span><span class="default">B</span><span class="default">,</span><span class="default">A</span><span class="default">,</span><span class="default">C</span><span class="default">] = </span><span class="functionid">invfreqs</span><span class="default">(</span><span class="default">H</span><span class="default">,</span><span class="default">F</span><span class="default">,</span><span class="default">nB</span><span class="default">,</span><span class="default">nA</span><span class="default">,</span><span class="default">W</span><span class="default">,</span><span class="default">iter</span><span class="default">,</span><span class="default">tol</span><span class="default">,</span><span class="default">trace</span><span class="default">)</span> <span class="default">[</span><span class="default">B</span><span class="default">,</span><span class="default">A</span><span class="default">,</span><span class="default">C</span><span class="default">] = </span><span class="functionid">invfreqs</span><span class="default">(</span><span class="default">H</span><span class="default">,</span><span class="default">F</span><span class="default">,</span><span class="default">nB</span><span class="default">,</span><span class="default">nA</span><span class="default">,</span><span class="default">W</span><span class="default">)</span> <span class="default">[</span><span class="default">B</span><span class="default">,</span><span class="default">A</span><span class="default">,</span><span class="default">C</span><span class="default">] = </span><span class="functionid">invfreqs</span><span class="default">(</span><span class="default">H</span><span class="default">,</span><span class="default">F</span><span class="default">,</span><span class="default">nB</span><span class="default">,</span><span class="default">nA</span><span class="default">)</span></pre></div></div> <div class="refsection"><h3 class="title">Parameters</h3> <dl><dt><span class="term">H:</span> <dd><p class="para">desired complex frequency response.</p></dd></dt> <dt><span class="term">F:</span> <dd><p class="para">frequency (must be same length as H).</p></dd></dt> <dt><span class="term">nB:</span> <dd><p class="para">order of the numerator polynomial B.</p></dd></dt> <dt><span class="term">nA:</span> <dd><p class="para">order of the denominator polynomial A.</p></dd></dt> <dt><span class="term">W:</span> <dd><p class="para">vector of weights (must be same length as F).</p></dd></dt></dl></div> <div class="refsection"><h3 class="title">Description</h3> <p class="para">This is an Octave function. Fit filter B(s)/A(s)to the complex frequency response H at frequency points F. A and B are real polynomial coefficients of order nA and nB. Optionally, the fit-errors can be weighted vs frequency according to the weights W. Note: all the guts are in invfreq.m</p></div> <div class="refsection"><h3 class="title">Examples</h3> <div class="programlisting"><table border="0" width="100%"><tr><td width="98%"><pre class="scilabcode"><span class="scilabid">B</span> <span class="scilaboperator">=</span> <span class="scilabopenclose">[</span><span class="scilabnumber">1</span><span class="scilaboperator">/</span><span class="scilabnumber">2</span> <span class="scilabnumber">1</span><span class="scilabopenclose">]</span><span class="scilabdefault">;</span> <span class="scilabid">A</span> <span class="scilaboperator">=</span> <span class="scilabopenclose">[</span><span class="scilabnumber">1</span> <span class="scilabnumber">1</span><span class="scilabopenclose">]</span><span class="scilabdefault">;</span> <span class="scilabid">w</span> <span class="scilaboperator">=</span> <a class="scilabmacro" href="scilab://linspace">linspace</a><span class="scilabopenclose">(</span><span class="scilabnumber">0</span><span class="scilabdefault">,</span><span class="scilabnumber">4</span><span class="scilabdefault">,</span><span class="scilabnumber">128</span><span class="scilabopenclose">)</span><span class="scilabdefault">;</span> <span class="scilabid">H</span> <span class="scilaboperator">=</span> <span class="scilabid">freqs</span><span class="scilabopenclose">(</span><span class="scilabid">B</span><span class="scilabdefault">,</span><span class="scilabid">A</span><span class="scilabdefault">,</span><span class="scilabid">w</span><span class="scilabopenclose">)</span><span class="scilabdefault">;</span> <span class="scilabopenclose">[</span><span class="scilabid">Bh</span><span class="scilabdefault">,</span><span class="scilabid">Ah</span><span class="scilabdefault">,</span> <span class="scilabid">C</span><span class="scilabopenclose">]</span> <span class="scilaboperator">=</span> <span class="scilabid">invfreqs</span><span class="scilabopenclose">(</span><span class="scilabid">H</span><span class="scilabdefault">,</span><span class="scilabid">w</span><span class="scilabdefault">,</span><span class="scilabnumber">1</span><span class="scilabdefault">,</span><span class="scilabnumber">1</span><span class="scilabopenclose">)</span><span class="scilabdefault">;</span> <span class="scilabid">Bh</span> <span class="scilaboperator">=</span> <span class="scilabnumber">0.50000</span> <span class="scilabnumber">1.00000</span> <span class="scilabid">Ah</span> <span class="scilaboperator">=</span> <span class="scilabnumber">1.0000</span> <span class="scilabnumber">1.0000</span> <span class="scilabid">C</span> <span class="scilaboperator">=</span> <span class="scilaboperator">-</span><span class="scilabnumber">3.0964e-15</span></pre></td><td valign="top"><a href="scilab://scilab.execexample/"><img src="ScilabExecute.png" border="0"/></a></td><td valign="top"><a href="scilab://scilab.editexample/"><img src="ScilabEdit.png" border="0"/></a></td><td></td></tr></table></div></div> <br /> <div class="manualnavbar"> <table width="100%"> <tr><td colspan="3" class="next"><a href="http://bugzilla.scilab.org/enter_bug.cgi?product=Scilab%20software&component=Documentation%20pages" class="ulink">Report an issue</a></td></tr> <tr> <td width="30%"> <span class="previous"><a href="invfreq.html"><< invfreq</a></span> </td> <td width="40%" class="center"> <span class="top"><a href="section_cc2bc01c47967d47fcf3507a91d572ba.html">FOSSEE Signal Processing Toolbox</a></span> </td> <td width="30%" class="next"> <span class="next"><a href="invfreqz.html">invfreqz >></a></span> </td> </tr></table> <hr /> </div> </body> </html>