f $\eta$.
It then computes $\eta$ for you, as a solution of the Primitive Element
Problem, using :py:func:`~.primitive_element` on the list of $\alpha_i$.

Examples
========

>>> from sympy import sqrt, to_number_field
>>> eta = sqrt(2)
>>> theta = sqrt(2) + sqrt(3)
>>> a = to_number_field(eta, theta)
>>> print(type(a))
<class 'sympy.core.numbers.AlgebraicNumber'>
>>> a.root
sqrt(2) + sqrt(3)
>>> print(a)
sqrt(2)
>>> a.coeffs()
[1/2, 0, -9/2, 0]

We get an :py:class:`~.AlgebraicNumber`, whose ``.root`` is $\theta$, whose
value is $\eta$, and whose ``.coeffs()`` show how to write $\eta$ as a
$\mathbb{Q}$-linear combination in falling powers of $\theta$.

Parameters
==========

extension : :py:class:`~.Expr` or list of :py:class:`~.Expr`
    Either the algebraic number that is to be expressed in the other field,
    or else a list of algebraic numbers, a primitive element for which is
    to be expressed in the other field.
theta : :py:class:`~.Expr`, None, optional (default=None)
    If an :py:class:`~.Expr` representing an algebraic number, behavior is
    as described under **Explanation**. If ``None``, then this function
    reduces to a shorthand for calling :py:func:`~.primitive_element` on
    ``extension`` and turning the computed primitive element into an
    :py:class:`~.AlgebraicNumber`.
gen : :py:class:`~.Symbol`, None, optional (default=None)
    If provided, this will be used as the generator symbol for the minimal
    polynomial in the returned :py:class:`~.AlgebraicNumber`.
alias : str, :py:class:`~.Symbol`, None, optional (default=None)
    If provided, this will be used as the alias symbol for the returned
    :py:class:`~.AlgebraicNumber`.

Returns
=======

AlgebraicNumber
    Belonging to $\mathbb{Q}(\theta)$ and equaling $\eta$.

Raises
======

IsomorphismFailed
    If $\eta \not\in \mathbb{Q}(\theta)$.

See Also
========

field_isomorphism
primitive_element

Ú__iter__r