<?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>isDirectSum -- whether something is a direct sum</title> <link rel="stylesheet" type="text/css" href="../../../../Macaulay2/Style/doc.css"/> </head> <body> <table class="buttons"> <tr> <td><div><a href="_is__Field.html">next</a> | <a href="_is__Constant.html">previous</a> | <a href="_is__Field.html">forward</a> | <a href="_is__Constant.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>isDirectSum -- whether something is a direct sum</h1> <div class="single"><h2>Description</h2> <div>Works for modules, graded modules, etc. The components of the sum can be recovered with <a href="_components.html" title="list the components of a direct sum">components</a>.<table class="examples"><tr><td><pre>i1 : isDirectSum ZZ^6 o1 = false</pre> </td></tr> <tr><td><pre>i2 : F = ZZ^2 ++ ZZ^3 5 o2 = ZZ o2 : ZZ-module, free</pre> </td></tr> <tr><td><pre>i3 : isDirectSum F o3 = true</pre> </td></tr> <tr><td><pre>i4 : components F 2 3 o4 = {ZZ , ZZ } o4 : List</pre> </td></tr> </table> </div> </div> <div class="waystouse"><h2>Ways to use <tt>isDirectSum</tt> :</h2> <ul><li>isDirectSum(ChainComplex)</li> <li>isDirectSum(GradedModule)</li> <li>isDirectSum(Module)</li> </ul> </div> </div> </body> </html>