com.opengamma.analytics.math.curve.ConstantDoublesCurve.java Source code

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Here is the source code for com.opengamma.analytics.math.curve.ConstantDoublesCurve.java

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/**
 * Copyright (C) 2009 - present by OpenGamma Inc. and the OpenGamma group of companies
 * 
 * Please see distribution for license.
 */
package com.opengamma.analytics.math.curve;

import java.util.Arrays;

import org.apache.commons.lang.Validate;

import com.opengamma.analytics.math.interpolation.Interpolator1D;

/**
 * Defines a constant curve (i.e. a curve with <i>y = constant</i>)
 */
public class ConstantDoublesCurve extends DoublesCurve {

    /**
     * @param y Level of the curve
     * @return A constant curve with automatically-generated name
     */
    public static ConstantDoublesCurve from(final double y) {
        return new ConstantDoublesCurve(y);
    }

    /**
     * 
     * @param y Level of the curve
     * @param name Name of the curve
     * @return A constant curve
     */
    public static ConstantDoublesCurve from(final double y, final String name) {
        return new ConstantDoublesCurve(y, name);
    }

    private final double _y;

    /**
     * 
     * @param y The level of the curve
     */
    public ConstantDoublesCurve(final double y) {
        super();
        _y = y;
    }

    /**
     * 
     * @param y The level of the curve
     * @param name The name of the curve
     */
    public ConstantDoublesCurve(final double y, final String name) {
        super(name);
        _y = y;
    }

    /**
     * @return Not supported
     * @throws UnsupportedOperationException
     */
    @Override
    public Double[] getXData() {
        throw new UnsupportedOperationException("Cannot get x data for constant curve");
    }

    /**
     * @return An array containing one element (the level)
     */
    @Override
    public Double[] getYData() {
        return new Double[] { _y };
    }

    /**
     * @param x The value
     * @return The level
     */
    @Override
    public Double getYValue(final Double x) {
        return _y;
    }

    @Override
    public Double[] getYValueParameterSensitivity(final Double x) {
        return new Double[] { 1.0d };
    }

    /**
     * 
     * @param x An array of <i>x</i> values, not null
     * @param interpolator An interpolator, not null
     * @return An interpolated curve with constant value 
     */
    public InterpolatedDoublesCurve toInterpolatedDoublesCurve(final double[] x,
            final Interpolator1D interpolator) {
        Validate.notNull(x, "x");
        Validate.notNull(interpolator, "interpolator");
        final double[] y = new double[x.length];
        Arrays.fill(y, _y);
        return InterpolatedDoublesCurve.from(x, y, interpolator);
    }

    /**
     * @return The size of the curve is one
     */
    @Override
    public int size() {
        return 1;
    }

    @Override
    public int hashCode() {
        final int prime = 31;
        int result = super.hashCode();
        long temp;
        temp = Double.doubleToLongBits(_y);
        result = prime * result + (int) (temp ^ (temp >>> 32));
        return result;
    }

    @Override
    public boolean equals(final Object obj) {
        if (this == obj) {
            return true;
        }
        if (!super.equals(obj)) {
            return false;
        }
        if (getClass() != obj.getClass()) {
            return false;
        }
        final ConstantDoublesCurve other = (ConstantDoublesCurve) obj;
        return Double.doubleToLongBits(_y) == Double.doubleToLongBits(other._y);
    }

    @Override
    public String toString() {
        return "ConstantDoublesCurve[name=" + getName() + ", y=" + _y + "]";
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public double getDyDx(final double x) {
        return 0;
    }
}