org.hipparchus.analysis.polynomials

## Class PolynomialFunctionNewtonForm

• java.lang.Object
• org.hipparchus.analysis.polynomials.PolynomialFunctionNewtonForm
• All Implemented Interfaces:
UnivariateDifferentiableFunction, FieldUnivariateFunction, UnivariateFunction

public class PolynomialFunctionNewtonForm
extends Object
implements UnivariateDifferentiableFunction, FieldUnivariateFunction
Implements the representation of a real polynomial function in Newton Form. For reference, see Elementary Numerical Analysis, ISBN 0070124477, chapter 2.

The formula of polynomial in Newton form is p(x) = a[0] + a[1](x-c[0]) + a[2](x-c[0])(x-c[1]) + ... + a[n](x-c[0])(x-c[1])...(x-c[n-1]) Note that the length of a[] is one more than the length of c[]

• ### Constructor Summary

Constructors
Constructor and Description
PolynomialFunctionNewtonForm(double[] a, double[] c)
Construct a Newton polynomial with the given a[] and c[].
• ### Method Summary

All Methods
Modifier and Type Method and Description
protected void computeCoefficients()
Calculate the normal polynomial coefficients given the Newton form.
int degree()
Returns the degree of the polynomial.
static double evaluate(double[] a, double[] c, double z)
Evaluate the Newton polynomial using nested multiplication.
double[] getCenters()
Returns a copy of the centers array.
double[] getCoefficients()
Returns a copy of the coefficients array.
double[] getNewtonCoefficients()
Returns a copy of coefficients in Newton form formula.
double value(double z)
Calculate the function value at the given point.
<T extends Derivative<T>>T value(T t)
Compute the value for the function.
<T extends CalculusFieldElement<T>>T value(T t)
Compute the value of the function.
protected static void verifyInputArray(double[] a, double[] c)
Verifies that the input arrays are valid.
• ### Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
• ### Methods inherited from interface org.hipparchus.analysis.FieldUnivariateFunction

toCalculusFieldUnivariateFunction
• ### Constructor Detail

• #### PolynomialFunctionNewtonForm

public PolynomialFunctionNewtonForm(double[] a,
double[] c)
throws MathIllegalArgumentException,
NullArgumentException
Construct a Newton polynomial with the given a[] and c[]. The order of centers are important in that if c[] shuffle, then values of a[] would completely change, not just a permutation of old a[].

The constructor makes copy of the input arrays and assigns them.

Parameters:
a - Coefficients in Newton form formula.
c - Centers.
Throws:
NullArgumentException - if any argument is null.
MathIllegalArgumentException - if any array has zero length.
MathIllegalArgumentException - if the size difference between a and c is not equal to 1.
• ### Method Detail

• #### value

public double value(double z)
Calculate the function value at the given point.
Specified by:
value in interface UnivariateFunction
Parameters:
z - Point at which the function value is to be computed.
Returns:
the function value.
• #### value

public <T extends Derivative<T>> T value(T t)
Compute the value for the function.
Specified by:
value in interface UnivariateDifferentiableFunction
Type Parameters:
T - the type of the field elements
Parameters:
t - the point for which the function value should be computed
Returns:
the value
• #### value

public <T extends CalculusFieldElement<T>> T value(T t)
Compute the value of the function.
Specified by:
value in interface FieldUnivariateFunction
Type Parameters:
T - the type of the field elements
Parameters:
t - Point at which the function value should be computed.
Returns:
the value of the function.
• #### degree

public int degree()
Returns the degree of the polynomial.
Returns:
the degree of the polynomial
• #### getNewtonCoefficients

public double[] getNewtonCoefficients()
Returns a copy of coefficients in Newton form formula.

Changes made to the returned copy will not affect the polynomial.

Returns:
a fresh copy of coefficients in Newton form formula
• #### getCenters

public double[] getCenters()
Returns a copy of the centers array.

Changes made to the returned copy will not affect the polynomial.

Returns:
a fresh copy of the centers array.
• #### getCoefficients

public double[] getCoefficients()
Returns a copy of the coefficients array.

Changes made to the returned copy will not affect the polynomial.

Returns:
a fresh copy of the coefficients array.
• #### evaluate

public static double evaluate(double[] a,
double[] c,
double z)
throws MathIllegalArgumentException,
NullArgumentException
Evaluate the Newton polynomial using nested multiplication. It is also called Horner's Rule and takes O(N) time.
Parameters:
a - Coefficients in Newton form formula.
c - Centers.
z - Point at which the function value is to be computed.
Returns:
the function value.
Throws:
NullArgumentException - if any argument is null.
MathIllegalArgumentException - if any array has zero length.
MathIllegalArgumentException - if the size difference between a and c is not equal to 1.
• #### computeCoefficients

protected void computeCoefficients()
Calculate the normal polynomial coefficients given the Newton form. It also uses nested multiplication but takes O(N^2) time.
• #### verifyInputArray

protected static void verifyInputArray(double[] a,
double[] c)
throws MathIllegalArgumentException,
NullArgumentException
Verifies that the input arrays are valid.

The centers must be distinct for interpolation purposes, but not for general use. Thus it is not verified here.

Parameters:
a - the coefficients in Newton form formula
c - the centers
Throws:
NullArgumentException - if any argument is null.
MathIllegalArgumentException - if any array has zero length.
MathIllegalArgumentException - if the size difference between a and c is not equal to 1.
DividedDifferenceInterpolator.computeDividedDifference(double[], double[])