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<div><a href="index.html" title="">Macaulay2Doc</a> > <a href="___The_sp__Macaulay2_splanguage.html" title="">The Macaulay2 language</a> > <a href="_operators.html" title="">operators</a> > <a href="__us.html" title="a binary operator, used for subscripting and access to elements">_</a></div>
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<div><h1>_ -- a binary operator, used for subscripting and access to elements</h1>
<div><!--empty documentation body--></div>
<div class="waystouse"><h2>Ways to use <tt>_</tt> :</h2>
<ul><li><span><a href="___Chain__Complex_sp_us_sp__Z__Z.html" title="component">ChainComplex _ ZZ</a> -- component</span></li>
<li><span>GradedModule _ ZZ, see <span><a href="___Chain__Complex_sp_us_sp__Z__Z.html" title="component">ChainComplex _ ZZ</a> -- component</span></span></li>
<li><span><a href="___Chain__Complex_sp_us_sp__Z__Z_sp_eq_sp__Thing.html" title="install component of chain complex">ChainComplex _ ZZ = Thing</a> -- install component of chain complex</span></li>
<li><span><a href="___Chain__Complex__Map_sp_us_sp__Z__Z.html" title="component map">ChainComplexMap _ ZZ</a> -- component map</span></li>
<li><span>GradedModuleMap _ ZZ, see <span><a href="___Chain__Complex__Map_sp_us_sp__Z__Z.html" title="component map">ChainComplexMap _ ZZ</a> -- component map</span></span></li>
<li><span><a href="___Chain__Complex__Map_sp_us_sp__Z__Z_sp_eq_sp__Thing.html" title="install component of chain complex map">ChainComplexMap _ ZZ = Thing</a> -- install component of chain complex map</span></li>
<li><span>Expression _ Expression, see <span><a href="___Expression.html" title="the class of all expressions">Expression</a> -- the class of all expressions</span></span></li>
<li><span><a href="___Function_sp_us_sp__Thing.html" title="attach the first argument to a function of two or more arguments">Function _ Thing</a> -- attach the first argument to a function of two or more arguments</span></li>
<li><span>Ideal _ ZZ, see <span><a href="_generators_spof_spideals_spand_spmodules.html" title="">generators of ideals and modules</a></span></span></li>
<li><span>Matrix _ ZZ, see <span><a href="_generators_spof_spideals_spand_spmodules.html" title="">generators of ideals and modules</a></span></span></li>
<li><span>Module _ ZZ, see <span><a href="_generators_spof_spideals_spand_spmodules.html" title="">generators of ideals and modules</a></span></span></li>
<li><span>MonomialIdeal _ ZZ, see <span><a href="_generators_spof_spideals_spand_spmodules.html" title="">generators of ideals and modules</a></span></span></li>
<li><span><a href="___Indexed__Variable_sp_us_sp__Ring.html" title="get a ring variable by name">IndexedVariable _ Ring</a> -- get a ring variable by name</span></li>
<li><span>IndexedVariableTable _ Thing, see <span><a href="___Indexed__Variable__Table.html" title="">IndexedVariableTable</a></span></span></li>
<li><span>IndexedVariableTable _ Thing = Thing, see <span><a href="___Indexed__Variable__Table.html" title="">IndexedVariableTable</a></span></span></li>
<li><span>ChainComplexMap _ Array, see <span><a href="___Matrix_sp_us_sp__Array.html" title="component of map corresponding to summand of source">Matrix _ Array</a> -- component of map corresponding to summand of source</span></span></li>
<li><span>GradedModuleMap _ Array, see <span><a href="___Matrix_sp_us_sp__Array.html" title="component of map corresponding to summand of source">Matrix _ Array</a> -- component of map corresponding to summand of source</span></span></li>
<li><span><a href="___Matrix_sp_us_sp__Array.html" title="component of map corresponding to summand of source">Matrix _ Array</a> -- component of map corresponding to summand of source</span></li>
<li><span><a href="___Matrix_sp_us_sp__List.html" title="select columns">Matrix _ List</a> -- select columns</span></li>
<li><span><a href="___Matrix_sp_us_sp__Sequence.html" title="get entry of matrix">Matrix _ Sequence</a> -- get entry of matrix</span></li>
<li><span>MutableMatrix _ Sequence, see <span><a href="___Matrix_sp_us_sp__Sequence.html" title="get entry of matrix">Matrix _ Sequence</a> -- get entry of matrix</span></span></li>
<li><span>ChainComplex _ Array, see <span><a href="___Module_sp_us_sp__Array.html" title="inclusion from summand">Module _ Array</a> -- inclusion from summand</span></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>Ideal _ List, see <span><a href="___Module_sp_us_sp__List.html" title="map from free module to some generators">Module _ List</a> -- map from free module to some generators</span></span></li>
<li><span><a href="___Module_sp_us_sp__List.html" title="map from free module to some generators">Module _ List</a> -- map from free module to some generators</span></li>
<li><span><a href="___Mutable__Matrix_sp_us_sp__Sequence_sp_eq_sp__Thing.html" title="assignment to an element of a mutable matrix">MutableMatrix _ Sequence = Thing</a> -- assignment to an element of a mutable matrix</span></li>
<li><span><a href="___Partition_sp_us_sp__Z__Z.html" title="get element">Partition _ ZZ</a> -- get element</span></li>
<li><span>Number _ Ring, see <span><a href="_promote.html" title="promote to another ring">promote</a> -- promote to another ring</span></span></li>
<li><span>RingElement _ Ring, see <span><a href="_promote.html" title="promote to another ring">promote</a> -- promote to another ring</span></span></li>
<li><span><a href="___Ring_sp_us_sp__List.html" title="make a monomial from a list of exponents">Ring _ List</a> -- make a monomial from a list of exponents</span></li>
<li><span><a href="___Ring_sp_us_sp__String.html" title="get a ring variable by name">Ring _ String</a> -- get a ring variable by name</span></li>
<li><span><a href="___Ring_sp_us_sp__Z__Z.html" title="get a ring variable by index">Ring _ ZZ</a> -- get a ring variable by index</span></li>
<li><span>SchurRingIndexedVariableTable _ Thing, see <span><a href="../../SchurRings/html/___Schur__Ring__Indexed__Variable__Table.html" title="">SchurRingIndexedVariableTable</a></span></span></li>
<li><span>ScriptedFunctor _ Thing, see <span><a href="___Scripted__Functor.html" title="the class of all scripted functors">ScriptedFunctor</a> -- the class of all scripted functors</span></span></li>
<li><span><a href="___String_sp_us_sp__Sequence.html" title="substring">String _ Sequence</a> -- substring</span></li>
<li><span><a href="___String_sp_us_sp__Z__Z.html" title="get element from string">String _ ZZ</a> -- get element from string</span></li>
<li><span><a href="___Symbol_sp_us_sp__Ring.html" title="get a ring variable by name">Symbol _ Ring</a> -- get a ring variable by name</span></li>
<li><span><a href="___Symbol_sp_us_sp__Thing.html" title="index variable">Symbol _ Thing</a> -- index variable</span></li>
<li><span><a href="___Symbol_sp_us_sp__Thing_sp_eq_sp__Thing.html" title="assignment to an indexed variable">Symbol _ Thing = Thing</a> -- assignment to an indexed variable</span></li>
<li><span><a href="___Tally_sp_us_sp__Thing.html" title="get a count from a tally">Tally _ Thing</a> -- get a count from a tally</span></li>
<li><span><a href="___Visible__List_sp_us_sp__List.html" title="get some entries of a list">VisibleList _ List</a> -- get some entries of a list</span></li>
<li><span><a href="___Visible__List_sp_us_sp__Z__Z.html" title="get element from list">VisibleList _ ZZ</a> -- get element from list</span></li>
<li><span><a href="___Z__Z_sp_us_sp__Module.html" title="integers or zero element">ZZ _ Module</a> -- integers or zero element</span></li>
</ul>
</div>
<div class="waystouse"><h2>For the programmer</h2>
<p>The object <a href="__us.html" title="a binary operator, used for subscripting and access to elements">_</a> is <span>a <a href="___Keyword.html">keyword</a></span>.</p>
<div><div><p>This operator may be used as a binary operator in an expression like <tt>x_y</tt>. The user may install <a href="_binary_spmethods.html" title="">binary methods</a> for handling such expressions with code such as</p>
<pre> X _ Y := (x,y) -> ...</pre>
<p>where <tt>X</tt> is the class of <tt>x</tt> and <tt>Y</tt> is the class of <tt>y</tt>.</p>
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