# double -- Double Reduced Ideal

## Synopsis

• Usage:
K=double(J)
• Inputs:
• J, an integral ideal
• Outputs:

## Description

The function double computes the reduced ideal of J*J given an integral ideal J. double(J) and add(J,J) outputs the same but double(J) is often more useful in practice.

 i1 : setPolynomialRing({x,y},{2,3}); setQuotientRing(y^2-x^3-7*x); J=ideal(x,y) o3 = ideal (x, y) o3 : Ideal of QR i4 : double J o4 = ideal 1 o4 : Ideal of QR i5 : reduced(J*J) o5 = ideal 1 o5 : Ideal of QR i6 : add(J,J) o6 = ideal 1 o6 : Ideal of QR