/**
* 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 com.opengamma.analytics.math.function.Function;
import com.opengamma.util.ArgumentChecker;
/**
* A function that performs addition on each of the constituent curves.
* <p>
* Given a number of curves $C_1(x_{i_1}, y_{i_1}) , C_2(x_{i_2}, y_{i_2}), \ldots C_n(x_{i_n}, y_{i_n})$, returns a function $F$
* that for a value $x$ will return:
* $$
* \begin{eqnarray*}
* F(x) = C_1 |_x + C_2 |_x + \ldots + C_n |_x
* \end{eqnarray*}
* $$
*/
public class AddCurveSpreadFunction implements CurveSpreadFunction {
/** The operation name */
public static final String NAME = "+";
/** An instance of this function */
private static final AddCurveSpreadFunction INSTANCE = new AddCurveSpreadFunction();
/**
* Gets an instance of this function
* @return The instance
*/
public static CurveSpreadFunction getInstance() {
return INSTANCE;
}
/**
* @deprecated Use {@link #getInstance()}
*/
@Deprecated
public AddCurveSpreadFunction() {
}
/**
* @param curves An array of curves, not null or empty
* @return A function that will find the value of each curve at the given input <i>x</i> and return the sum of these values
*/
@SuppressWarnings("unchecked")
@Override
public Function<Double, Double> evaluate(final Curve<Double, Double>... curves) {
ArgumentChecker.notNull(curves, "x");
ArgumentChecker.notEmpty(curves, "curves");
return new Function<Double, Double>() {
@Override
public Double evaluate(final Double... x) {
ArgumentChecker.notNull(x, "x");
ArgumentChecker.notEmpty(x, "x");
final double x0 = x[0];
double y = curves[0].getYValue(x0);
for (int i = 1; i < curves.length; i++) {
y += curves[i].getYValue(x0);
}
return y;
}
};
}
@Override
public String getOperationName() {
return NAME;
}
@Override
public String getName() {
return NAME;
}
}