Difference between revisions of "ApCoCoA-1:NCo.LC"

From ApCoCoAWiki
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<title>NCo.LC</title>
 
<title>NCo.LC</title>
 
<short_description>
 
<short_description>
The leading coefficient of a polynomial in a free monoid ring.
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The leading coefficient of a non-zero polynomial in a free monoid ring.
 
</short_description>
 
</short_description>
 
<syntax>
 
<syntax>
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Please set ring environment <em>coefficient field</em> <tt> K</tt>, <em>alphabet</em> (or set of indeterminates) <tt>X</tt> and <em>ordering</em> via the functions <ref>NCo.SetFp</ref>, <ref>NCo.SetX</ref> and <ref>NCo.SetOrdering</ref>, respectively, before using this function. The default coefficient field is <tt>Q</tt>, and the default ordering is length-lexicographic ordering (<quotes>LLEX</quotes>). For more information, please check the relevant functions.
 
Please set ring environment <em>coefficient field</em> <tt> K</tt>, <em>alphabet</em> (or set of indeterminates) <tt>X</tt> and <em>ordering</em> via the functions <ref>NCo.SetFp</ref>, <ref>NCo.SetX</ref> and <ref>NCo.SetOrdering</ref>, respectively, before using this function. The default coefficient field is <tt>Q</tt>, and the default ordering is length-lexicographic ordering (<quotes>LLEX</quotes>). For more information, please check the relevant functions.
 
<itemize>
 
<itemize>
<item>@param <em>F</em>: a polynomial in <tt>K&lt;X&gt;</tt>. Each polynomial is represented as a LIST of monomials, which are LISTs of the form [C, W] where W is a word in <tt>&lt;X&gt;</tt> and C is the coefficient of W. For example, the polynomial <tt>F=xy-y+1</tt> is represented as F:=[[1,<quotes>xy</quotes>], [-1, <quotes>y</quotes>], [1,<quotes></quotes>]]. The zero polynomial <tt>0</tt> is represented as the empty LIST [].</item>
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<item>@param <em>F</em>: a non-zero polynomial in <tt>K&lt;X&gt;</tt>. Each polynomial is represented as a LIST of monomials, which are LISTs of the form [C, W] where W is a word in <tt>&lt;X&gt;</tt> and C is the coefficient of W. For example, the polynomial <tt>F=xy-y+1</tt> is represented as F:=[[1,<quotes>xy</quotes>], [-1, <quotes>y</quotes>], [1,<quotes></quotes>]]. The zero polynomial <tt>0</tt> is represented as the empty LIST [].</item>
 
<item>@return: a INT or RAT, which represents the leading coefficient of F with respect to the current word ordering. If <tt>F=0</tt>, the function returns <tt>0</tt>.</item>
 
<item>@return: a INT or RAT, which represents the leading coefficient of F with respect to the current word ordering. If <tt>F=0</tt>, the function returns <tt>0</tt>.</item>
 
</itemize>
 
</itemize>

Revision as of 16:42, 29 April 2013

NCo.LC

The leading coefficient of a non-zero polynomial in a free monoid ring.

Syntax

NCo.LC(F:LIST):INT or RAT

Description

Please note: The function(s) explained on this page is/are using the ApCoCoAServer. You will have to start the ApCoCoAServer in order to use it/them.

Please set ring environment coefficient field K, alphabet (or set of indeterminates) X and ordering via the functions NCo.SetFp, NCo.SetX and NCo.SetOrdering, respectively, before using this function. The default coefficient field is Q, and the default ordering is length-lexicographic ordering ("LLEX"). For more information, please check the relevant functions.

  • @param F: a non-zero polynomial in K<X>. Each polynomial is represented as a LIST of monomials, which are LISTs of the form [C, W] where W is a word in <X> and C is the coefficient of W. For example, the polynomial F=xy-y+1 is represented as F:=[[1,"xy"], [-1, "y"], [1,""]]. The zero polynomial 0 is represented as the empty LIST [].

  • @return: a INT or RAT, which represents the leading coefficient of F with respect to the current word ordering. If F=0, the function returns 0.

Example

NCo.SetX(<quotes>abc</quotes>);
F:=[[1,<quotes>ab</quotes>],[2,<quotes>aa</quotes>],[3,<quotes>bb</quotes>],[4,<quotes>bab</quotes>]];
NCo.SetOrdering(<quotes>ELIM</quotes>);
NCo.LC(F);
2
-------------------------------
NCo.SetOrdering(<quotes>LLEX</quotes>);
NCo.LC(F);
4
-------------------------------
NCo.LC([]); -- 0 polynomial
0
-------------------------------

See also

NCo.SetFp

NCo.SetOrdering

NCo.SetX

Introduction to CoCoAServer