NewtonBasis
Newton polynomials on a set of nodes
Calling Sequence
Parameters
Description
Examples
NewtonBasis(k, nodes, x)
k
-
algebraic expression; the index
nodes
list of algebraic expressions; nodes where the polynomial is known
x
algebraic expression; the argument
The kth Newton polynomial of degree k is defined by
NewtonBasis⁡k,nodes,x=∏j=0k−1⁡x−nodesj
By convention, the nodes are indexed from 0, so nodes=[x0,x1,...,xn].
At present, this can only be evaluated in Maple by prior use of the object-oriented representation obtained by P:=convert(p,MatrixPolynomialObject,x) and subsequent call to P:-Value(<x-value>), which uses Horner's method to evaluate the polynomial p.
nodes≔−1,−13,13,1
p≔3⁢NewtonBasis⁡0,nodes,x+5⁢NewtonBasis⁡2,nodes,x+7⁢NewtonBasis⁡3,nodes,x
p≔3⁢NewtonBasis⁡0,−1,−13,13,1,x+5⁢NewtonBasis⁡2,−1,−13,13,1,x+7⁢NewtonBasis⁡3,−1,−13,13,1,x
The coefficients of that polynomial can be interpreted in terms of divided differences of the values of p at the nodes.
P≔convert⁡p,MatrixPolynomialObject,x
P≔Record⁡Value=Defaultvalue,Variable=x,Degree=3,Coefficient=coe,Dimension=1,1,Basis=NewtonBasis,BasisParameters=−1,−13,13,1,IsMonic=mon,OutputOptions=shape=,storage=rectangular,order=Fortran_order,fill=0,attributes=
P:-Degree⁡
3
Note that the result returned by convert⁡...,MatrixPolynomialObject represents a matrix polynomial; hence these results are 1 by 1 matrices.
seq⁡P:-Value⁡nodesk1,1,k=1..nops⁡nodes
3,3,679,2599
P:-Value⁡0.3
6.924555556
factor⁡P:-Value⁡t1,1
7⁢t3+12⁢t2+539⁢t+359
See Also
BernsteinBasis
convert/MatrixPolynomialObject
LagrangeBasis
LinearAlgebra[CompanionMatrix]
OrthogonalSeries
PochhammerBasis
type/MatrixPolynomialObject
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