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<a name="Miscellaneous-Functions"></a>
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>
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<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.
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<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>.
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<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.
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<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>
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