com.opengamma.strata.math.impl.function

Class RealPolynomialFunction1D

java.lang.Object

com.opengamma.strata.math.impl.function.RealPolynomialFunction1D

All Implemented Interfaces:

DoubleFunction1D, DoubleUnaryOperator

public class RealPolynomialFunction1D
extends Object
implements DoubleFunction1D

Class representing a polynomial that has real coefficients and takes a real argument. The function is defined as: $$ \begin{align*} p(x) = a_0 + a_1 x + a_2 x^2 + \ldots + a_{n-1} x^{n-1} \end{align*} $$

Constructor Summary

Constructors

Constructor and Description
RealPolynomialFunction1D(double... coefficients) Creates an instance.

Method Summary

Modifier and Type	Method and Description
RealPolynomialFunction1D	add(double a) Adds a constant to the polynomial (equivalent to adding the value to the constant term of the polynomial).
DoubleFunction1D	add(DoubleFunction1D f) Adds a function to the polynomial.
double	applyAsDouble(double x)
RealPolynomialFunction1D	derivative() Returns the derivative of this polynomial (also a polynomial), where $$ \begin{align*} P'(x) = a_1 + 2 a_2 x + 3 a_3 x^2 + 4 a_4 x^3 + \dots + n a_n x^{n-1} \end{align*} $$.
RealPolynomialFunction1D	divide(double a) Divides the polynomial by a constant value (equivalent to dividing each coefficient by this value).
boolean	equals(Object obj)
double[]	getCoefficients() Gets the coefficients of this polynomial.
int	hashCode()
RealPolynomialFunction1D	multiply(double a) Multiplies the polynomial by a constant value (equivalent to multiplying each coefficient by this value).
DoubleFunction1D	multiply(DoubleFunction1D f) Multiplies the polynomial by a function.
RealPolynomialFunction1D	subtract(double a) Subtracts a constant from the polynomial (equivalent to subtracting the value from the constant term of the polynomial).
DoubleFunction1D	subtract(DoubleFunction1D f) Subtracts a function from the polynomial.
RealPolynomialFunction1D	toMonic() Converts the polynomial to its monic form.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface com.opengamma.strata.math.impl.function.DoubleFunction1D

derivative, divide, from

Methods inherited from interface java.util.function.DoubleUnaryOperator

andThen, compose, identity

Constructor Detail

RealPolynomialFunction1D

public RealPolynomialFunction1D(double... coefficients)

Creates an instance. The array of coefficients for a polynomial $p(x) = a_0 + a_1 x + a_2 x^2 + ... + a_{n-1} x^{n-1}$ is $\\{a_0, a_1, a_2, ..., a_{n-1}\\}$.

Parameters:

coefficients - the array of coefficients, not null or empty

Method Detail

applyAsDouble

public double applyAsDouble(double x)

Specified by:

applyAsDouble in interface DoubleUnaryOperator

getCoefficients

public double[] getCoefficients()

Gets the coefficients of this polynomial.

Returns:

the coefficients of this polynomial

add

public DoubleFunction1D add(DoubleFunction1D f)

Adds a function to the polynomial. If the function is not a RealPolynomialFunction1D then the addition takes place as in DoubleFunction1D, otherwise the result will also be a polynomial.

Specified by:

add in interface DoubleFunction1D

Parameters:

f - the function to add

Returns:

$P+f$

add

public RealPolynomialFunction1D add(double a)

Adds a constant to the polynomial (equivalent to adding the value to the constant term of the polynomial). The result is also a polynomial.

Specified by:

add in interface DoubleFunction1D

Parameters:

a - the value to add

Returns:

$P+a$

derivative

public RealPolynomialFunction1D derivative()

Returns the derivative of this polynomial (also a polynomial), where $$ \begin{align*} P'(x) = a_1 + 2 a_2 x + 3 a_3 x^2 + 4 a_4 x^3 + \dots + n a_n x^{n-1} \end{align*} $$.

Specified by:

derivative in interface DoubleFunction1D

Returns:

the derivative polynomial

divide

public RealPolynomialFunction1D divide(double a)

Divides the polynomial by a constant value (equivalent to dividing each coefficient by this value). The result is also a polynomial.

Specified by:

divide in interface DoubleFunction1D

Parameters:

a - the divisor

Returns:

the polynomial

multiply

public DoubleFunction1D multiply(DoubleFunction1D f)

Multiplies the polynomial by a function. If the function is not a RealPolynomialFunction1D then the multiplication takes place as in DoubleFunction1D, otherwise the result will also be a polynomial.

Specified by:

multiply in interface DoubleFunction1D

Parameters:

f - the function by which to multiply

Returns:

$P \dot f$

multiply

public RealPolynomialFunction1D multiply(double a)

Multiplies the polynomial by a constant value (equivalent to multiplying each coefficient by this value). The result is also a polynomial.

Specified by:

multiply in interface DoubleFunction1D

Parameters:

a - the multiplicator

Returns:

the polynomial

subtract

public DoubleFunction1D subtract(DoubleFunction1D f)

Subtracts a function from the polynomial.

If the function is not a RealPolynomialFunction1D then the subtract takes place as in DoubleFunction1D, otherwise the result will also be a polynomial.

Specified by:

subtract in interface DoubleFunction1D

Parameters:

f - the function to subtract

Returns:

$P-f$

subtract

public RealPolynomialFunction1D subtract(double a)

Subtracts a constant from the polynomial (equivalent to subtracting the value from the constant term of the polynomial). The result is also a polynomial.

Specified by:

subtract in interface DoubleFunction1D

Parameters:

a - the value to add

Returns:

$P-a$

toMonic

public RealPolynomialFunction1D toMonic()

Converts the polynomial to its monic form. If $$ \begin{align*} P(x) = a_0 + a_1 x + a_2 x^2 + a_3 x^3 \dots + a_n x^n \end{align*} $$ then the monic form is $$ \begin{align*} P(x) = \lambda_0 + \lambda_1 x + \lambda_2 x^2 + \lambda_3 x^3 \dots + x^n \end{align*} $$ where $$ \begin{align*} \lambda_i = \frac{a_i}{a_n} \end{align*} $$

Returns:

the polynomial in monic form

equals

public boolean equals(Object obj)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object