Class PolynomialFunction

    • Constructor Detail

      • PolynomialFunction

        public PolynomialFunction​(double[] c)
        Construct a polynomial with the given coefficients. The first element of the coefficients array is the constant term. Higher degree coefficients follow in sequence. The degree of the resulting polynomial is the index of the last non-null element of the array, or 0 if all elements are null.

        The constructor makes a copy of the input array and assigns the copy to the coefficients property.

        Parameters:
        c - polynomial coefficients
        Throws:
        java.lang.NullPointerException - if c is null
        NoDataException - if c is empty
    • Method Detail

      • value

        public double value​(double x)
        Compute the value of the function for the given argument.

        The value returned is
        coefficients[n] * x^n + ... + coefficients[1] * x + coefficients[0]

        Specified by:
        value in interface UnivariateRealFunction
        Parameters:
        x - the argument for which the function value should be computed
        Returns:
        the value of the polynomial at the given point
        See Also:
        UnivariateRealFunction.value(double)
      • degree

        public int degree()
        Returns the degree of the polynomial
        Returns:
        the degree of the polynomial
      • getCoefficients

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

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

        Returns:
        a fresh copy of the coefficients array
      • evaluate

        protected static double evaluate​(double[] coefficients,
                                         double argument)
        Uses Horner's Method to evaluate the polynomial with the given coefficients at the argument.
        Parameters:
        coefficients - the coefficients of the polynomial to evaluate
        argument - the input value
        Returns:
        the value of the polynomial
        Throws:
        NoDataException - if coefficients is empty
        java.lang.NullPointerException - if coefficients is null
      • add

        public PolynomialFunction add​(PolynomialFunction p)
        Add a polynomial to the instance.
        Parameters:
        p - polynomial to add
        Returns:
        a new polynomial which is the sum of the instance and p
      • subtract

        public PolynomialFunction subtract​(PolynomialFunction p)
        Subtract a polynomial from the instance.
        Parameters:
        p - polynomial to subtract
        Returns:
        a new polynomial which is the difference the instance minus p
      • negate

        public PolynomialFunction negate()
        Negate the instance.
        Returns:
        a new polynomial
      • multiply

        public PolynomialFunction multiply​(PolynomialFunction p)
        Multiply the instance by a polynomial.
        Parameters:
        p - polynomial to multiply by
        Returns:
        a new polynomial
      • differentiate

        protected static double[] differentiate​(double[] coefficients)
        Returns the coefficients of the derivative of the polynomial with the given coefficients.
        Parameters:
        coefficients - the coefficients of the polynomial to differentiate
        Returns:
        the coefficients of the derivative or null if coefficients has length 1.
        Throws:
        NoDataException - if coefficients is empty
        java.lang.NullPointerException - if coefficients is null
      • polynomialDerivative

        public PolynomialFunction polynomialDerivative()
        Returns the derivative as a PolynomialRealFunction
        Returns:
        the derivative polynomial
      • toString

        public java.lang.String toString()
        Returns a string representation of the polynomial.

        The representation is user oriented. Terms are displayed lowest degrees first. The multiplications signs, coefficients equals to one and null terms are not displayed (except if the polynomial is 0, in which case the 0 constant term is displayed). Addition of terms with negative coefficients are replaced by subtraction of terms with positive coefficients except for the first displayed term (i.e. we display -3 for a constant negative polynomial, but 1 - 3 x + x^2 if the negative coefficient is not the first one displayed).

        Overrides:
        toString in class java.lang.Object
        Returns:
        a string representation of the polynomial
      • hashCode

        public int hashCode()
        Overrides:
        hashCode in class java.lang.Object
      • equals

        public boolean equals​(java.lang.Object obj)
        Overrides:
        equals in class java.lang.Object