# Gridap.Polynomials

Gridap.Polynomials.MonomialBasisType
struct MonomialBasis{D,T} <: AbstractVector{Monomial}

Type representing a basis of multivariate scalar-valued, vector-valued, or tensor-valued, iso- or aniso-tropic monomials. The fields of this struct are not public. This type fully implements the Field interface, with up to second order derivatives.

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Gridap.Polynomials.MonomialBasisMethod
MonomialBasis{D}(::Type{T}, order::Int [, filter::Function]) where {D,T}

Returns an instance of MonomialBasis representing a multivariate polynomial basis in D dimensions, of polynomial degree order, whose value is represented by the type T. The type T is typically <:Number, e.g., Float64 for scalar-valued functions and VectorValue{D,Float64} for vector-valued ones.

Filter function

The filter function is used to select which terms of the tensor product space of order order in D dimensions are to be used. If the filter is not provided, the full tensor-product space is used by default leading to a multivariate polynomial space of type Q. The signature of the filter function is

(e,order) -> Bool

where e is a tuple of D integers containing the exponents of a multivariate monomial. The following filters are used to select well known polynomial spaces

• Q space: (e,order) -> true
• P space: (e,order) -> sum(e) <= order
• "Serendipity" space: (e,order) -> sum( [ i for i in e if i>1 ] ) <= order
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Gridap.Polynomials.MonomialBasisMethod
MonomialBasis{D}(::Type{T}, orders::Tuple [, filter::Function]) where {D,T}

This version of the constructor allows to pass a tuple orders containing the polynomial order to be used in each of the D dimensions in order to construct an anisotropic tensor-product space.

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Gridap.Polynomials.PCurlGradMonomialBasisType

This type implements a multivariate vector-valued polynomial basis spanning the space needed for Raviart-Thomas reference elements on simplices. The type parameters and fields of this struct are not public. This type fully implements the Field interface, with up to first order derivatives.

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Gridap.Polynomials.PCurlGradMonomialBasisMethod

Returns a PCurlGradMonomialBasis object. D is the dimension of the coordinate space and T is the type of the components in the vector-value. The order argument has the following meaning: the divergence of the functions in this basis is in the P space of degree order.

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Gridap.Polynomials.QCurlGradMonomialBasisType
struct QCurlGradMonomialBasis{...} <: AbstractArray{Monomial}

This type implements a multivariate vector-valued polynomial basis spanning the space needed for Raviart-Thomas reference elements on n-cubes. The type parameters and fields of this struct are not public. This type fully implements the Field interface, with up to first order derivatives.

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Gridap.Polynomials.QCurlGradMonomialBasisMethod
QCurlGradMonomialBasis{D}(::Type{T},order::Int) where {D,T}

Returns a QCurlGradMonomialBasis object. D is the dimension of the coordinate space and T is the type of the components in the vector-value. The order argument has the following meaning: the divergence of the functions in this basis is in the Q space of degree order.

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Gridap.Polynomials.QGradMonomialBasisType
struct QGradMonomialBasis{...} <: AbstractVector{Monomial}

This type implements a multivariate vector-valued polynomial basis spanning the space needed for Nedelec reference elements on n-cubes. The type parameters and fields of this struct are not public. This type fully implements the Field interface, with up to first order derivatives.

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Gridap.Polynomials.QGradMonomialBasisMethod
QGradMonomialBasis{D}(::Type{T},order::Int) where {D,T}

Returns a QGradMonomialBasis object. D is the dimension of the coordinate space and T is the type of the components in the vector-value. The order argument has the following meaning: the curl of the functions in this basis is in the Q space of degree order.

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Gridap.Polynomials.get_exponentsMethod
get_exponents(b::MonomialBasis)

Get a vector of tuples with the exponents of all the terms in the monomial basis.

Examples

using Gridap.Polynomials

b = MonomialBasis{2}(Float64,2)

exponents = get_exponents(b)

println(exponents)

# output
Tuple{Int,Int}[(0, 0), (1, 0), (2, 0), (0, 1), (1, 1), (2, 1), (0, 2), (1, 2), (2, 2)]
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