org.ddogleg.solver

Class Polynomial

java.lang.Object

org.ddogleg.solver.Polynomial

public class Polynomial
extends java.lang.Object

Data structure for storing polynomials. Internally the coefficients are stored in an array from lowest degree to highest:
f(x) = c[0] + c[1]*x + ... + c[n]*x^n-1

Field Summary

Fields

Modifier and Type	Field and Description
double[]	c
int	size

Constructor Summary

Constructors

Constructor and Description
Polynomial(int maxCoefficients) Creates a polynomial which can hold the specified number of coefficients.
Polynomial(Polynomial original)

Method Summary

Modifier and Type	Method and Description
int	computeDegree() Finds the power of the largest non-zero coefficient in the polynomial.
double	evaluate(double variable) Computes the polynomials output given the variable value Can handle infinite numbers
double	get(int i)
double[]	getCoefficients()
boolean	isIdentical(Polynomial p, double tol) Checks to see if the coefficients of two polynomials are identical to within tolerance.
void	print()
void	resize(int size) Change the maximum number of coefficients which can be stored inside this polynomial
void	setTo(double[] coefficients, int size)
void	setTo(Polynomial source)
int	size()
java.lang.String	toString()
void	truncateZeros(double tol) Prunes zero coefficients from the end of a sequence.
static Polynomial	wrap(double... coefficients) Wraps the polynomial around the array: f(x) = c[0] + c[1]*x + ...
void	zero()

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

c

public double[] c

size

public int size

Constructor Detail

Polynomial

public Polynomial(int maxCoefficients)

Creates a polynomial which can hold the specified number of coefficients. Note this is the polynomial's degree+1.

Parameters:

maxCoefficients - The largest number of coefficients which can be stored. Also the initial size of the polynomial.

Polynomial

public Polynomial(Polynomial original)

Method Detail

wrap

public static Polynomial wrap(double... coefficients)

Wraps the polynomial around the array:
f(x) = c[0] + c[1]*x + ... + c[n]*x^n-1

Parameters:

coefficients - Polynomial coefficients

Returns:

new instance of a polyonimial which is identical to the input array

evaluate

public double evaluate(double variable)

Computes the polynomials output given the variable value Can handle infinite numbers

Returns:

Output

setTo

public void setTo(Polynomial source)

setTo

public void setTo(double[] coefficients,
                  int size)

resize

public void resize(int size)

Change the maximum number of coefficients which can be stored inside this polynomial

Parameters:

size - New maximum number of coefficients.

zero

public void zero()

computeDegree

public int computeDegree()

Finds the power of the largest non-zero coefficient in the polynomial. If all the coefficients are zero or if there is only the constant term, zero is returned.

Returns:

Degree of the polynomial

isIdentical

public boolean isIdentical(Polynomial p,
                           double tol)

Checks to see if the coefficients of two polynomials are identical to within tolerance. If the lengths of the polynomials are not the same then the extra coefficients in the longer polynomial must be within tolerance of zero.

Parameters:

p - Polynomial that this polynomial is being compared against.

tol - Similarity tolerance. Try 1e-15 for high confidence

Returns:

true if the two polynomials are identical to within tolerance.

truncateZeros

public void truncateZeros(double tol)

Prunes zero coefficients from the end of a sequence. A coefficient is zero if its absolute value is less than or equal to tolerance.

Parameters:

tol - Tolerance for zero. Try 1e-15

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

print

public void print()

getCoefficients

public double[] getCoefficients()

size

public int size()

get

public double get(int i)