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2.11.1 Introduction to RINGELEM

An object of type RINGELEM in CoCoA represents an element of a ring.

To fix terminology about polynomials (elements of a polynomial ring): a polynomial is a sum of terms; each term is the product of a coefficient and power-product, and a power-product is a product of powers of indeterminates.

In English it is standard to use monomial to mean a power-product, however, in other languages, such as Italian, monomial connotes a power-product multiplied by a scalar. In the interest of world peace, we will use the term power-product in those cases where confusion may arise.

Example

/**/ use P ::= QQ[x,y,z]; /**/ f := 3*x*y*z + x*y^2; /**/ f; x*y^2 + 3*x*y*z ------------------------------- /**/ use P ::= QQ[x[1..5]]; /**/ sum([x[N]^2 | N in 1..5]); x[1]^2 + x[2]^2 + x[3]^2 + x[4]^2 + x[5]^2 -------------------------------

CoCoA always keeps polynomials ordered with respect to the term-orderings of their corresponding rings.

The following algebraic operations on polynomials are supported:

  F^N, +F, -F, F*G, F/G if G divides F, F+G, F-G,

where F, G are polynomials and N is an integer. The result may be a rational function.

Example

/**/ use R ::= QQ[x,y,z]; /**/ F := x^2 +x*y; /**/ G := x; /**/ F/G; x + y -- /**/ F/(x+z); --> !!! ERROR !!! as expected: Inexact division /**/ F^2; x^4 +2*x^3*y +x^2*y^2