<html lang="en">
<head>
<title>Miscellaneous Functions - Untitled</title>
<meta http-equiv="Content-Type" content="text/html">
<meta name="description" content="Untitled">
<meta name="generator" content="makeinfo 4.13">
<link title="Top" rel="start" href="index.html#Top">
<link rel="up" href="Polynomial-Manipulations.html#Polynomial-Manipulations" title="Polynomial Manipulations">
<link rel="prev" href="Polynomial-Interpolation.html#Polynomial-Interpolation" title="Polynomial Interpolation">
<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage">
<meta http-equiv="Content-Style-Type" content="text/css">
<style type="text/css"><!--
pre.display { font-family:inherit }
pre.format { font-family:inherit }
pre.smalldisplay { font-family:inherit; font-size:smaller }
pre.smallformat { font-family:inherit; font-size:smaller }
pre.smallexample { font-size:smaller }
pre.smalllisp { font-size:smaller }
span.sc { font-variant:small-caps }
span.roman { font-family:serif; font-weight:normal; }
span.sansserif { font-family:sans-serif; font-weight:normal; }
--></style>
</head>
<body>
<div class="node">
<a name="Miscellaneous-Functions"></a>
<p>
Previous: <a rel="previous" accesskey="p" href="Polynomial-Interpolation.html#Polynomial-Interpolation">Polynomial Interpolation</a>,
Up: <a rel="up" accesskey="u" href="Polynomial-Manipulations.html#Polynomial-Manipulations">Polynomial Manipulations</a>
<hr>
</div>
<h3 class="section">27.6 Miscellaneous Functions</h3>
<!-- ./polynomial/poly.m -->
<p><a name="doc_002dpoly"></a>
<div class="defun">
— Function File: <b>poly</b> (<var>a</var>)<var><a name="index-poly-2053"></a></var><br>
<blockquote><p>If <var>a</var> is a square N-by-N matrix, <code>poly (</code><var>a</var><code>)</code>
is the row vector of the coefficients of <code>det (z * eye (N) - a)</code>,
the characteristic polynomial of <var>a</var>. As an example we can use
this to find the eigenvalues of <var>a</var> as the roots of <code>poly (</code><var>a</var><code>)</code>.
<pre class="example"> roots(poly(eye(3)))
⇒ 1.00000 + 0.00000i
⇒ 1.00000 - 0.00000i
⇒ 1.00000 + 0.00000i
</pre>
<p>In real-life examples you should, however, use the <code>eig</code> function
for computing eigenvalues.
<p>If <var>x</var> is a vector, <code>poly (</code><var>x</var><code>)</code> is a vector of coefficients
of the polynomial whose roots are the elements of <var>x</var>. That is,
of <var>c</var> is a polynomial, then the elements of
<var>d</var><code> = roots (poly (</code><var>c</var><code>))</code> are contained in <var>c</var>.
The vectors <var>c</var> and <var>d</var> are, however, not equal due to sorting
and numerical errors.
<!-- Texinfo @sp should work but in practice produces ugly results for HTML. -->
<!-- A simple blank line produces the correct behavior. -->
<!-- @sp 1 -->
<p class="noindent"><strong>See also:</strong> <a href="doc_002deig.html#doc_002deig">eig</a>, <a href="doc_002droots.html#doc_002droots">roots</a>.
</p></blockquote></div>
<!-- ./polynomial/polyout.m -->
<p><a name="doc_002dpolyout"></a>
<div class="defun">
— Function File: <b>polyout</b> (<var>c, x</var>)<var><a name="index-polyout-2054"></a></var><br>
<blockquote><p>Write formatted polynomial
<pre class="example"> c(x) = c(1) * x^n + ... + c(n) x + c(n+1)
</pre>
<p>and return it as a string or write it to the screen (if
<var>nargout</var> is zero).
<var>x</var> defaults to the string <code>"s"</code>.
<!-- Texinfo @sp should work but in practice produces ugly results for HTML. -->
<!-- A simple blank line produces the correct behavior. -->
<!-- @sp 1 -->
<p class="noindent"><strong>See also:</strong> <a href="doc_002dpolyval.html#doc_002dpolyval">polyval</a>, <a href="doc_002dpolyvalm.html#doc_002dpolyvalm">polyvalm</a>, <a href="doc_002dpoly.html#doc_002dpoly">poly</a>, <a href="doc_002droots.html#doc_002droots">roots</a>, <a href="doc_002dconv.html#doc_002dconv">conv</a>, <a href="doc_002ddeconv.html#doc_002ddeconv">deconv</a>, <a href="doc_002dresidue.html#doc_002dresidue">residue</a>, <a href="doc_002dfilter.html#doc_002dfilter">filter</a>, <a href="doc_002dpolyderiv.html#doc_002dpolyderiv">polyderiv</a>, <a href="doc_002dpolyinteg.html#doc_002dpolyinteg">polyinteg</a>.
</p></blockquote></div>
<!-- ./polynomial/polyreduce.m -->
<p><a name="doc_002dpolyreduce"></a>
<div class="defun">
— Function File: <b>polyreduce</b> (<var>c</var>)<var><a name="index-polyreduce-2055"></a></var><br>
<blockquote><p>Reduces a polynomial coefficient vector to a minimum number of terms by
stripping off any leading zeros.
<!-- Texinfo @sp should work but in practice produces ugly results for HTML. -->
<!-- A simple blank line produces the correct behavior. -->
<!-- @sp 1 -->
<p class="noindent"><strong>See also:</strong> <a href="doc_002dpoly.html#doc_002dpoly">poly</a>, <a href="doc_002droots.html#doc_002droots">roots</a>, <a href="doc_002dconv.html#doc_002dconv">conv</a>, <a href="doc_002ddeconv.html#doc_002ddeconv">deconv</a>, <a href="doc_002dresidue.html#doc_002dresidue">residue</a>, <a href="doc_002dfilter.html#doc_002dfilter">filter</a>, <a href="doc_002dpolyval.html#doc_002dpolyval">polyval</a>, <a href="doc_002dpolyvalm.html#doc_002dpolyvalm">polyvalm</a>, <a href="doc_002dpolyderiv.html#doc_002dpolyderiv">polyderiv</a>, <a href="doc_002dpolyinteg.html#doc_002dpolyinteg">polyinteg</a>.
</p></blockquote></div>
<!-- DO NOT EDIT! Generated automatically by munge-texi. -->
<!-- Copyright (C) 2007, 2008, 2009 John W. Eaton -->
<!-- This file is part of Octave. -->
<!-- Octave is free software; you can redistribute it and/or modify it -->
<!-- under the terms of the GNU General Public License as published by the -->
<!-- Free Software Foundation; either version 3 of the License, or (at -->
<!-- your option) any later version. -->
<!-- Octave is distributed in the hope that it will be useful, but WITHOUT -->
<!-- ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or -->
<!-- FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License -->
<!-- for more details. -->
<!-- You should have received a copy of the GNU General Public License -->
<!-- along with Octave; see the file COPYING. If not, see -->
<!-- <http://www.gnu.org/licenses/>. -->
</body></html>
distrib
>
Mandriva
>
2010.0
>
i586
>
media
>
contrib-release
>
by-pkgid
>
3e60ff9d4d6f58c8fbd17208f14089fa
>
files
>
280
