File r37/lisp/csl/html/r37_0436.html artifact bb51a6fc76 part of check-in trunk

<A NAME=REALROOTS>

<TITLE>REALROOTS</TITLE></A>
<b><a href=r37_idx.html>INDEX</a></b><p><p>



<B>REALROOTS</B> _ _ _  _ _ _  _ _ _  _ _ _ <B>operator</B><P>
<P>
 
 <P>
<P>
The operator <em>realroots</em> finds that real roots of a polynomial 
to an accuracy that is sufficient to separate them and which is 
a minimum of 6 decimal places. 
<P>
<P>
 <P> <H3> 
syntax: </H3>
<em>realroots</em>(&lt;p&gt;) or 
<P>
<P>
<em>realroots</em>(&lt;p&gt;,&lt;from&gt;,&lt;to&gt;) 
<P>
<P>
<P>
where &lt;p&gt; is a univariate polynomial. 
The optional parameters &lt;from&gt; and &lt;to&gt; classify 
an interval: if given, exactly the real roots in this 
interval will be returned. &lt;from&gt; and &lt;to&gt; 
can also take the values <em>infinity</em> or <em>-infinity</em>. 
If omitted all real roots will be returned. 
Result is a 
<A HREF=r37_0053.html>list</A> 
of equations which represent the roots of the polynomial at the 
given accuracy. 
<P>
<P>
 <P> <H3> 
examples: </H3>
<P><PRE><TT>
realroots(x^5-2);

  {x=1.1487}


realroots(x^3-104*x^2+403*x-300,2,infinity);


  {x=3.0,x=100.0}


realroots(x^3-104*x^2+403*x-300,-infinity,2);


  {x=1}

</TT></PRE><P>The minimal accuracy of the result values is controlled by 

<A HREF=r37_0437.html>rootacc</A>. 
<P>
<P>