# AlgebraicUnitQ

yields True if a is an algebraic unit, and yields False otherwise.

# Details • AlgebraicUnitQ is typically used to test whether a number is an algebraic unity or not.
• An algebraic unit a is a number for which both a and 1/a are algebraic integers.
• • returns False unless a is manifestly an algebraic unit.

# Examples

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## Basic Examples(2)

Test whether a number is an algebraic unit:

The number is not an algebraic unit:

## Scope(4)

AlgebraicUnitQ works over integers:

Real numbers:

Complex numbers:

Transcendental numbers:

Root objects:

AlgebraicNumber objects:

## Applications(6)

### Basic Applications(1)

Generate random algebraic units:

Plot algebraic units:

### Number Theory(5)

Find integers that are algebraic units:

All roots of unity are algebraic units:

An algebraic unit has norm or :

Representatives of norm in :

It can be represented in terms of the representative a by multiplying by a unit:

Use the roots of unity to find Cyclotomic polynomials:

## Properties & Relations(7)

An algebraic unit and its reciprocal are algebraic integers:

The reciprocal is an algebraic unit:

The only integers that are both algebraic integers and algebraic units are and :

An algebraic unit raised to a power is an algebraic unit:

Algebraics represents the domain of all algebraic numbers, including algebraic units:

An algebraic unit has norm or :

Use MinimalPolynomial to find the minimal polynomial of an algebraic unit:

Now find the minimal polynomial of its reciprocal:

Fundamental units of a number field are algebraic units:

## Possible Issues(1)

In some cases it is not known whether the number is an algebraic unit: