plotfunction.java~1~

来自「一个一元曲线多项式数值演示例子」· JAVA~1~ 代码 · 共 188 行

package numbercruncher.rootutils;

import java.util.*;
import java.awt.*;

import numbercruncher.graphutils.Plottable;
import numbercruncher.graphutils.PlotProperties;
import numbercruncher.mathutils.Function;
import numbercruncher.mathutils.Evaluatable;
import numbercruncher.rootutils.RootFunctions;

/**
 * Wrapper class that makes functions plottable.
 */
public class PlotFunction implements Plottable
{
    private static final int X1   =   1;
    private static final int X2   = 216;

    private static final int Y11A =  25;
    private static final int Y12A =  52;
    private static final int Y21A = Y12A + 2;
    private static final int Y22A =  82;
    private static final int Y31A = Y22A + 2;
    private static final int Y32A = 111;
    private static final int Y41A = Y32A + 2;
    private static final int Y42A = 141;
    private static final int Y51A = Y42A + 2;
    private static final int Y52A = 170;
    private static final int Y61A = Y52A + 2;
    private static final int Y62A = 200;
    private static final int Y71A = Y62A + 2;
    private static final int Y72A = 229;

    private static final int XL1  = 277;
    private static final int XL2  = 424;
    private static final int XR1  = XL2 + 2;
    private static final int XR2  = 539;

    private static final int Y11B =  24;
    private static final int Y12B =  92;
    private static final int Y21B = Y12B + 2;
    private static final int Y22B = 128;
    private static final int Y31B = Y22B + 2;
    private static final int Y32B = 174;
    private static final int Y41B = Y32B + 2;
    private static final int Y42B = 212;
    private static final int Y51B = Y42B + 2;
    private static final int Y52B = 264;
    private static final int Y61B = Y52B + 2;
    private static final int Y62B = 336;
    private static final int Y71B = Y62B + 2;
    private static final int Y72B = 388;
    private static final int Y81B = Y72B + 2;
    private static final int Y82B = 445;
    private static final int Y91B = Y82B + 2;
    private static final int Y92B = 506;

    /** function */         private Function       function;
    /** image region */     private Rectangle      rectangle;
    /** plot properties */  private PlotProperties properties;

    /** wrapped function table */
    private static Hashtable TABLE = new Hashtable(32);

    // Enter the wrapped functions into the table.
    static {
        enter("x^2 - 4",                X1,  Y11A, X2,  Y12A);
        enter("-x^2 + 4x + 5",          X1,  Y21A, X2,  Y22A);
        enter("x^3 + 3x^2 - 9x - 10",   X1,  Y31A, X2,  Y32A);
        enter("x^2 - 2x + 3",           X1,  Y41A, X2,  Y42A);
        enter("2x^3 - 10x^2 + 11x - 5", X1,  Y51A, X2,  Y52A);
        enter("e^-x - x",               X1,  Y61A, X2,  Y62A);
        enter("x - e^(1/x)",            X1,  Y71A, X2,  Y72A);
        enter("(x + 4/x)/2",            XL1, Y11B, XL2, Y12B);
        enter("4/x",                    XR1, Y11B, XR2, Y12B);
        enter("sqrt(x + 2)",            XL1, Y21B, XL2, Y22B);
        enter("2/x + 1",                XL1, Y31B, XL2, Y32B);
        enter("x*x - 2",                XR1, Y21B, XR2, Y22B);
        enter("exp(-x)",                XL1, Y41B, XL2, Y42B);
        enter("-log(x)",                XR1, Y41B, XR2, Y42B);
        enter("exp(1/x)",               XL1, Y51B, XL2, Y52B);
        enter("(x + exp(1/x))/2",       XL1, Y61B, XL2, Y62B);
        enter("1/log(x)",               XR1, Y51B, XR2, Y52B);
        enter("sin(x)/2 + 1",           XL1, Y71B, XL2, Y72B);
        enter("1 + 1/x + 1/(x*x)",      XL1, Y81B, XL2, Y82B);
        enter("20/(x*x + 2*x + 10)",    XL1, Y91B, XL2, Y92B);
    };

    /**
     * Create a wrapped function and enter it into the table.
     * @param key  the hash key
     * @param xMin the minimum x value of the plot bounds
     * @param xMax the maximum x value of the plot bounds
     * @param xMin the minimum y value of the plot bounds
     * @param yMax the maximum y value of the plot bounds
     */
    private static void enter(String key, int x1, int y1, int x2, int y2)
    {
        PlotFunction plotFunction = new PlotFunction(x1, y1, x2, y2);
        plotFunction.function = RootFunctions.function(key);

        TABLE.put(key, plotFunction);
    }

    /**
     * Constructor.
     * @param key the function key
     * @param x1 the x-coordinate of uppper left corner of image region
     * @param y1 the y-coordinate of uppper left corner of image region
     * @param x1 the x-coordinate of lower left corner of image region
     * @param y1 the y-coordinate of lower left corner of image region
     */
    public PlotFunction(String key,
                        float xMin, float xMax, float yMin, float yMax)
    {
        PlotFunction plotFunction = (PlotFunction) TABLE.get(key);

        if (plotFunction != null) {
            this.function   = plotFunction.function;
            this.rectangle  = plotFunction.rectangle;
            this.properties = new PlotProperties(xMin, xMax, yMin, yMax);
        }
    }

    /**
     * Constructor.
     * @param function the function
     * @param x1 the x-coordinate of uppper left corner of image region
     * @param y1 the y-coordinate of uppper left corner of image region
     * @param x1 the x-coordinate of lower left corner of image region
     * @param y1 the y-coordinate of lower left corner of image region
     */
    public PlotFunction(Function function,
                        float xMin, float xMax, float yMin, float yMax)
    {
        this.function   = function;
        this.rectangle  = null;
        this.properties = new PlotProperties(xMin, xMax, yMin, yMax);
    }

    /**
     * Constructor.
     * @param x1 the x-coordinate of uppper left corner of image region
     * @param y1 the y-coordinate of uppper left corner of image region
     * @param x1 the x-coordinate of lower left corner of image region
     * @param y1 the y-coordinate of lower left corner of image region
     */
    private PlotFunction(int x1, int y1, int x2, int y2)
    {
	rectangle = new Rectangle(x1, y1, x2-x1+1, y2-y1+1);
    }

    /**
     * Return the unwrapped function.
     * @return the function
     */
    public Evaluatable getFunction() { return function; }

    /**
     * Return the value of the function at x.
     * (Plottable implementation.)
     * @return the function value
     */
    public float at(float x) { return function.at(x); }

    /**
     * Return the value of the function's derivative at x.
     * @return the derivative value
     */
    public float derivativeAt(float x) { return function.derivativeAt(x); }

    //--------------------------//
    // Plottable implementation //
    //--------------------------//

    /**
     * Get the plot function's image rectangle
     * @return the rectangle
     */
    public Rectangle getRectangle() { return rectangle;  }

    /**
     * Get the plot function's properties
     * @return the properties
     */
    public PlotProperties getPlotProperties() { return properties; }
}