Macaulay2 » Documentation
Packages » TestIdeals :: testElement
next | previous | forward | backward | up | index | toc

testElement -- find a test element of a ring



Given $R = S/I$, where $S$ is a polynomial ring, the function testElement finds an element of the ambient ring $S$ whose image in $R$ is a test element of $R$. This is done by finding a minor of the jacobian of $I$ that does not lie in any minimal prime of $I$. This function considers random minors until one is found, instead of computing all minors. Thus, repeated calls will not always produce the same answer.

i1 : R = ZZ/11[x,y,z]/(x^3 + y^3 + z^3);
i2 : apply(1..5, i -> testElement(R))

         2     2    2    2    2
o2 = (-2y , -2z , -y , 2y , 4x )

o2 : Sequence

If the option AssumeDomain (default value false) is set to true, then testElement does not compute the minimal primes of $I$. This can result in a substantial speedup in some cases.

Ways to use testElement :

For the programmer

The object testElement is a method function with options.