SecantRootFinder
jhplot.math.num.root

Class SecantRootFinder



  • public class SecantRootFinderextends IterativeMethod

    The secant method (1) for finding roots of functions.

    For example, to find roots for sine, first a Function is defined:

     Function sine = new Function() {    public double evaluate(double x) {        return Math.sin(x);    }} }; 

    Then, a secant root finder is created with the above function:

     SecantRootFinder finder = new SecantRootFinder(sine); 

    Lastly, locating roots is accomplished using the findRoot(double, double) method:

     // find the root around 3 and 4. double pi = finder.findRoot(3.0, 4.0);  // find the root around 3.5 and 4. pi = finder.findRoot(3.5, 4.0);  // find the root around -1 and 1. double zero = finder.findRoot(-1.0, 1.0); 

    References:

    1. Eric W. Weisstein. "Secant Method." From MathWorld--A Wolfram Web Resource. http://mathworld.wolfram.com/SecantMethod.html

    • Constructor Detail

      • SecantRootFinder

        public SecantRootFinder(Function f)
        Create a root finder for the given function.
        Parameters:
        f - the target function.
      • SecantRootFinder

        public SecantRootFinder(Function f,                int iterations,                double error)
        Create a root finder for the given function.
        Parameters:
        f - the target function.
        iterations - maximum number of iterations.
        error - maximum relative error.
    • Method Detail

      • findRoot

        public double findRoot(double x0,              double x1)                throws NumericException
        Find a root of the target function that lies around the two initial approximations, x0 and x1.
        Parameters:
        x0 - an initial approximation to the root.
        x1 - another initial approximation to the root.
        Returns:
        a root that lies close to x0 and x1.
        Throws:
        NumericException - if a root could not be found.
      • getFunction

        public Function getFunction()
        Access the target function.
        Returns:
        the target function.
      • setFunction

        public void setFunction(Function f)
        Modify the target function.
        Parameters:
        f - the new target function.

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