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<head><title>Classic -- a parser for classic Macaulay syntax</title>
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<div><h1>Classic -- a parser for classic Macaulay syntax</h1>
<div class="single"><h2>Description</h2>
<div><p>This package provides a parser for polynomials in the classic Macaulay format. Some users prefer it, for ease and speed of typing polynomials, ideals, and matrices.</p>
<p>Only ring variables that are single letters, or single letters indexed by a sequence of numbers can be handled with this parser.</p>
<p>The rules for creating polynomials using the classic parser include:</p>
<ul><li>Spaces, tabs, and newline characters are completely ignored.</li>
<li>A variable is either (1) a single letter, (2) a subscripted variable, or (3) a polynomial enclosed in parentheses.</li>
<li>Subscripted variables, e.g., <tt>y_(1,1)</tt>, are written using brackets, as in <tt>y[1,1]</tt>. Instead of explicit numbers for subscripted variables, Macaulay2 user variables that have an integer value may be used.</li>
<li>Coefficients are either integers or rational numbers, starting with a + or - (which may be omitted for the first monomial). Over finite fields, the division is performed in that field.</li>
<li>A monomial is written without symbols for multiplication or exponentiation, where the (optional) coefficient comes first.</li>
<li>A polynomial is a collection of monomials one after the other.</li>
<li>Parenthesized subexpressions are allowed.</li>
<li>Except for indices for subscripted variables, integers must be explicitly given.</li>
<li>All of the variables used must already belong to a specific ring. If in doubt, first type <tt>use R</tt> to ensure that all the symbols of <tt>R</tt> are in use.</li>
</ul>
<p>The source code for this parser is relatively short, since it is based on the package <a href="../../Parsing/html/index.html" title="a framework for building parsers">Parsing</a>. Here it is.</p>
<table class="examples"><tr><td><pre>symbolP = (x -> (
if not isGlobalSymbol x then error("symbol ",x," undefined");
getGlobalSymbol x)) % letterParser
seqP = (comma, parser) -> prepend % parser @ * (last % comma @ parser)
variableP = value % symbolP
intP = NNParser | variableP
subscriptP = ((lb,x,rb) -> x) % andP( "[", unsequence % seqP_"," intP, "]" )
ringVariableP = ((x,n) -> value if n === nil then x else x_n) %
symbolP @ optP subscriptP
numberP = ZZParser | QQParser
powerP = ((x,n) -> if n === nil then x else x^n) %
(futureParser parenExprP | ringVariableP) @ optP NNParser
monomialP = times @@ deepSplice %
optionalSignParser @ (numberP @ *powerP | +powerP )
polyP = plus @@ deepSplice % +monomialP | terminalParser 0
parenExprP = ((l,x,r) -> x) % andP("(", futureParser parenExprP | polyP, ")")
listPolyP = toList % seqP_"," polyP
arrayPolyP = toList % seqP_";" listPolyP
export poly ; poly = method()
poly String := RingElement => polyP : nonspaceAnalyzer
ideal String := Ideal => ideal % listPolyP : nonspaceAnalyzer
monomialIdeal String := MonomialIdeal =>
monomialIdeal % listPolyP : nonspaceAnalyzer
matrix String := Matrix => opts ->
matrix_opts % arrayPolyP : nonspaceAnalyzer</pre>
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<div class="single"><h2>Author</h2>
<ul><li><div class="single"><a href="http://www.math.uiuc.edu/~dan/">Daniel R. Grayson</a><span> <<a href="mailto:dan@math.uiuc.edu">dan@math.uiuc.edu</a>></span></div>
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<div class="single"><h2>Version</h2>
This documentation describes version <b>1.0</b> of Classic.</div>
<div class="single"><h2>Source code</h2>
The source code from which this documentation is derived is in the file <a href="../../../../Macaulay2/Classic.m2">Classic.m2</a>.</div>
<div class="single"><h2>Exports</h2>
<ul><li><div class="single">Functions<ul><li><span>poly, see <span><a href="_poly_lp__String_rp.html" title="make a polynomial using classic Macaulay syntax">poly(String)</a> -- make a polynomial using classic Macaulay syntax</span></span></li>
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<div><h3>Menu</h3>
<ul><li><span><a href="_poly_lp__String_rp.html" title="make a polynomial using classic Macaulay syntax">poly(String)</a> -- make a polynomial using classic Macaulay syntax</span></li>
<li><span><a href="_ideal_lp__String_rp.html" title="make an ideal using classic Macaulay syntax">ideal(String)</a> -- make an ideal using classic Macaulay syntax</span></li>
<li><span><a href="_matrix_lp__String_rp.html" title="make a matrix using classic Macaulay syntax">matrix(String)</a> -- make a matrix using classic Macaulay syntax</span></li>
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