order and degree of polynomial

Let $f$ be a polynomial in two variables, viz. $f(x,y)=\sum_{i,j}a_{ij}x^{i}y^{j}$ .¹¹In order to simplify the notation, the definition is given in terms of a polynomial in two variables, however the definition naturally scales to any number of variables.

Then the total degree of $f$ is given by:

\mathrm{deg}f=\sup\{i+j|a_{ij}\neq 0\}

Note the degree of the zero-polynomial is $-\infty$ , since $\sup\emptyset$ (per definition) is $-\infty$ , thus $\mathrm{deg}f\in\mathbb{N}\cup\{0\}\cup\{-\infty\}$ .

Similarly the order of $f$ is given by:

\mathrm{ord}f=\inf\{i+j|a_{ij}\neq 0\}

Note the order of the zero-polynomial is $\infty$ (because $\inf\emptyset=\infty$ ). Thus $\mathrm{ord}f\in\mathbb{N}\cup\{0\}\cup\{\infty\}$ .

Please note that the term order is not as common as degree. In fact, it is perhaps more frequently associated with power series (a form of generalized polynomials) than with ordinary polynomials. Also be aware that the term order occasionally is used as a synonym for degree.

Title	order and degree of polynomial
Canonical name	OrderAndDegreeOfPolynomial
Date of creation	2013-03-22 13:38:21
Last modified on	2013-03-22 13:38:21
Owner	jgade (861)
Last modified by	jgade (861)
Numerical id	8
Author	jgade (861)
Entry type	Definition
Classification	msc 12-00
Related topic	ZeroPolynomial2
Defines	order
Defines	degree