<?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>Matrix ^ Array -- component of map corresponding to summand of target</title> <link rel="stylesheet" type="text/css" href="../../../../Macaulay2/Style/doc.css"/> </head> <body> <table class="buttons"> <tr> <td><div><a href="___Matrix_sp^_sp__List.html">next</a> | <a href="___Matrix_sp_sl_sl_sp__Matrix.html">previous</a> | <a href="___Matrix_sp^_sp__List.html">forward</a> | <a href="___Matrix_sp_sl_sl_sp__Matrix.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>Matrix ^ Array -- component of map corresponding to summand of target</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>F^[i,j,...,k]</tt></div> </dd></dl> </div> </li> <li><span>Operator: <a href="_^.html" title="a binary operator, usually used for powers">^</a></span></li> <li><div class="single">Inputs:<ul><li><span><tt>F</tt>, <span>a <a href="___Matrix.html">matrix</a></span>, or <span>a <a href="___Chain__Complex__Map.html">chain complex map</a></span> or <span>a <a href="___Graded__Module__Map.html">graded module map</a></span></span></li> <li><span><tt>[i,j,...,k]</tt>, an array of indices</span></li> </ul> </div> </li> <li><div class="single">Outputs:<ul><li><span><span>a <a href="___Matrix.html">matrix</a></span>, <span>a <a href="___Chain__Complex__Map.html">chain complex map</a></span>, or <span>a <a href="___Graded__Module__Map.html">graded module map</a></span></span></li> </ul> </div> </li> </ul> </div> <div class="single"><h2>Description</h2> <div>The target of the module or chain complex <tt>F</tt> should be a direct sum, and the result is the component of this map corresponding to the sum of the components numbered or named <tt>i, j, ..., k</tt>. Free modules are regarded as direct sums of modules. In otherwords, this routine returns the map given by certain blocks of columns.<table class="examples"><tr><td><pre>i1 : R = ZZ[a..d];</pre> </td></tr> <tr><td><pre>i2 : F = (vars R) ++ ((vars R) ++ matrix{{a-1,b-3},{c,d}}) o2 = | a b c d 0 0 0 0 0 0 | | 0 0 0 0 a b c d 0 0 | | 0 0 0 0 0 0 0 0 a-1 b-3 | | 0 0 0 0 0 0 0 0 c d | 4 10 o2 : Matrix R <--- R</pre> </td></tr> <tr><td><pre>i3 : F^[1] o3 = | 0 0 0 0 a b c d 0 0 | | 0 0 0 0 0 0 0 0 a-1 b-3 | | 0 0 0 0 0 0 0 0 c d | 3 10 o3 : Matrix R <--- R</pre> </td></tr> <tr><td><pre>i4 : F_[1]^[1] o4 = | a b c d 0 0 | | 0 0 0 0 a-1 b-3 | | 0 0 0 0 c d | 3 6 o4 : Matrix R <--- R</pre> </td></tr> </table> <p>If the components have been given names (see <a href="_direct__Sum.html" title="direct sum of modules or maps">directSum</a>), use those instead.</p> <table class="examples"><tr><td><pre>i5 : G = (a=>R^2) ++ (b=>R^1) 3 o5 = R o5 : R-module, free</pre> </td></tr> <tr><td><pre>i6 : N = map(G,R^2, (i,j) -> (i+37*j)_R) o6 = | 0 37 | | 1 38 | | 2 39 | 3 2 o6 : Matrix R <--- R</pre> </td></tr> <tr><td><pre>i7 : N^[a] o7 = | 0 37 | | 1 38 | 2 2 o7 : Matrix R <--- R</pre> </td></tr> <tr><td><pre>i8 : N^[b] o8 = | 2 39 | 1 2 o8 : Matrix R <--- R</pre> </td></tr> <tr><td><pre>i9 : N = directSum(x1 => matrix{{a,b-1}}, x2 => matrix{{a-3,b-17,c-35}}, x3 => vars R) o9 = | a b-1 0 0 0 0 0 0 0 | | 0 0 a-3 b-17 c-35 0 0 0 0 | | 0 0 0 0 0 a b c d | 3 9 o9 : Matrix R <--- R</pre> </td></tr> <tr><td><pre>i10 : N^[x1,x3] o10 = | a b-1 0 0 0 0 0 0 0 | | 0 0 0 0 0 a b c d | 2 9 o10 : Matrix R <--- R</pre> </td></tr> </table> <p>This works the same way for maps between chain complexes.</p> </div> </div> <div class="single"><h2>See also</h2> <ul><li><span><a href="___Matrix_sp^_sp__Array.html" title="component of map corresponding to summand of target">Matrix ^ Array</a> -- component of map corresponding to summand of target</span></li> <li><span><a href="___Module_sp_us_sp__Array.html" title="inclusion from summand">Module _ Array</a> -- inclusion from summand</span></li> <li><span><a href="_direct__Sum.html" title="direct sum of modules or maps">directSum</a> -- direct sum of modules or maps</span></li> </ul> </div> </div> </body> </html>