<?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>isANumber -- whether a number is a number</title> <link rel="stylesheet" type="text/css" href="../../../../Macaulay2/Style/doc.css"/> </head> <body> <table class="buttons"> <tr> <td><div><a href="_is__Borel.html">next</a> | <a href="_is__Affine__Ring.html">previous</a> | <a href="_is__Borel.html">forward</a> | <a href="_is__Affine__Ring.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>isANumber -- whether a number is a number</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>isANumber x</tt></div> </dd></dl> </div> </li> <li><div class="single">Inputs:<ul><li><span><tt>x</tt></span></li> </ul> </div> </li> <li><div class="single">Outputs:<ul><li><span><span>a <a href="___Boolean.html">Boolean value</a></span>, whether <tt>x</tt> is a number, i.e., is not <em>not a number</em>.</span></li> </ul> </div> </li> </ul> </div> <div class="single"><h2>Description</h2> <div><table class="examples"><tr><td><pre>i1 : isANumber 3. o1 = true</pre> </td></tr> <tr><td><pre>i2 : inf = 1/0. o2 = infinity o2 : RR (of precision 53)</pre> </td></tr> <tr><td><pre>i3 : isANumber inf o3 = true</pre> </td></tr> <tr><td><pre>i4 : nan = inf - inf o4 = NotANumber o4 : RR (of precision 53)</pre> </td></tr> <tr><td><pre>i5 : isANumber nan o5 = false</pre> </td></tr> </table> </div> </div> </div> </body> </html>