ModelStandardTransform.java

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package com.sun.gervill;

/**
 * A standard transformer used in connection blocks.
 * It expects input values to be between 0 and 1.
 *
 * The result of the transform is
 *   between 0 and 1 if polarity = unipolar and
 *   between -1 and 1 if polarity = bipolar.
 *
 * These constraints only applies to Concave, Convex and Switch transforms.
 *
 * @author Karl Helgason
 */
public final class ModelStandardTransform implements ModelTransform {

    public static final boolean DIRECTION_MIN2MAX = false;
    public static final boolean DIRECTION_MAX2MIN = true;
    public static final boolean POLARITY_UNIPOLAR = false;
    public static final boolean POLARITY_BIPOLAR = true;
    public static final int TRANSFORM_LINEAR = 0;
    // concave: output = (20*log10(127^2/value^2)) / 96
    public static final int TRANSFORM_CONCAVE = 1;
    // convex: same as concave except that start and end point are reversed.
    public static final int TRANSFORM_CONVEX = 2;
    // switch: if value > avg(max,min) then max else min
    public static final int TRANSFORM_SWITCH = 3;
    public static final int TRANSFORM_ABSOLUTE = 4;
    private boolean direction = DIRECTION_MIN2MAX;
    private boolean polarity = POLARITY_UNIPOLAR;
    private int transform = TRANSFORM_LINEAR;

    public ModelStandardTransform() {
    }

    public ModelStandardTransform(boolean direction) {
        this.direction = direction;
    }

    public ModelStandardTransform(boolean direction, boolean polarity) {
        this.direction = direction;
        this.polarity = polarity;
    }

    public ModelStandardTransform(boolean direction, boolean polarity,
            int transform) {
        this.direction = direction;
        this.polarity = polarity;
        this.transform = transform;
    }

    public double transform(double value) {
        double s;
        double a;
        if (direction == DIRECTION_MAX2MIN)
            value = 1.0 - value;
        if (polarity == POLARITY_BIPOLAR)
            value = value * 2.0 - 1.0;
        switch (transform) {
            case TRANSFORM_CONCAVE:
                s = Math.signum(value);
                a = Math.abs(value);
                a = -((5.0 / 12.0) / Math.log(10)) * Math.log(1.0 - a);
                if (a < 0)
                    a = 0;
                else if (a > 1)
                    a = 1;
                return s * a;
            case TRANSFORM_CONVEX:
                s = Math.signum(value);
                a = Math.abs(value);
                a = 1.0 + ((5.0 / 12.0) / Math.log(10)) * Math.log(a);
                if (a < 0)
                    a = 0;
                else if (a > 1)
                    a = 1;
                return s * a;
            case TRANSFORM_SWITCH:
                if (polarity == POLARITY_BIPOLAR)
                    return (value > 0) ? 1 : -1;
                else
                    return (value > 0.5) ? 1 : 0;
            case TRANSFORM_ABSOLUTE:
                return Math.abs(value);
            default:
                break;
        }

        return value;
    }

    public boolean getDirection() {
        return direction;
    }

    public void setDirection(boolean direction) {
        this.direction = direction;
    }

    public boolean getPolarity() {
        return polarity;
    }

    public void setPolarity(boolean polarity) {
        this.polarity = polarity;
    }

    public int getTransform() {
        return transform;
    }

    public void setTransform(int transform) {
        this.transform = transform;
    }
}