<?xml version="1.0" encoding="utf-8" ?> <!-- for emacs: -*- coding: utf-8 -*- --> <!-- Apache may like this line in the file .htaccess: AddCharset utf-8 .html --> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1 plus MathML 2.0 plus SVG 1.1//EN" "http://www.w3.org/2002/04/xhtml-math-svg/xhtml-math-svg-flat.dtd" > <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en"> <head><title>isUnit -- whether a ring element is a unit</title> <link rel="stylesheet" type="text/css" href="../../../../Macaulay2/Style/doc.css"/> </head> <body> <table class="buttons"> <tr> <td><div><a href="_is__Well__Defined.html">next</a> | <a href="_is__Table.html">previous</a> | <a href="_is__Well__Defined.html">forward</a> | <a href="_is__Table.html">backward</a> | up | <a href="index.html">top</a> | <a href="master.html">index</a> | <a href="toc.html">toc</a> | <a href="http://www.math.uiuc.edu/Macaulay2/">Macaulay2 web site</a></div> </td> </tr> </table> <hr/> <div><h1>isUnit -- whether a ring element is a unit</h1> <div class="single"><h2>Synopsis</h2> <ul><li><div class="list"><dl class="element"><dt class="heading">Usage: </dt><dd class="value"><div><tt>isUnit r</tt></div> </dd></dl> </div> </li> <li><div class="single">Inputs:<ul><li><span><tt>r</tt>, <span>a <a href="___Ring__Element.html">ring element</a></span></span></li> </ul> </div> </li> <li><div class="single">Outputs:<ul><li><span><span>a <a href="___Boolean.html">Boolean value</a></span>, <a href="_true.html" title="">true</a> if the <a href="___Ring__Element.html">ring element</a> <tt>r</tt> generates an ideal containing the multiplicative identity <tt>1</tt> and <tt>false</tt> otherwise</span></li> </ul> </div> </li> </ul> </div> <div class="single"><h2>Description</h2> <div><table class="examples"><tr><td><pre>i1 : R = QQ[z]/(z^2+1);</pre> </td></tr> <tr><td><pre>i2 : isUnit z o2 = true</pre> </td></tr> <tr><td><pre>i3 : S = QQ[x,y]/(1-(x-1)*(y-1));</pre> </td></tr> <tr><td><pre>i4 : isUnit (x^2 - 2*x + 1) o4 = true</pre> </td></tr> <tr><td><pre>i5 : isUnit x o5 = false</pre> </td></tr> </table> </div> </div> <div class="waystouse"><h2>Ways to use <tt>isUnit</tt> :</h2> <ul><li>isUnit(Number)</li> <li>isUnit(RingElement)</li> <li>isUnit(ZZ)</li> </ul> </div> </div> </body> </html>