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package com.accelad.math.nilgiri.autodiff;

import java.util.List;

import com.accelad.math.nilgiri.AbstractIdentityFactory;
import com.accelad.math.nilgiri.Field;


public class Constant> extends DifferentialFunction {

    private X m_x;
    private AbstractIdentityFactory m_factory;

    protected Constant(X i_v, AbstractIdentityFactory i_factory) {
        if (i_v != null && i_factory != null) {
            m_x = i_v;
            m_factory = i_factory;
        } else {
            throw new IllegalArgumentException("Input not null value.");
        }
    }

    protected AbstractIdentityFactory factory() {
        return m_factory;
    }

    @Override
    public boolean isConstant() {
        return true;
    }

    @Override
    public X getValue() {
        return m_x;
    }

    @Override
    public double getReal() {
        return m_x.getReal();
    }

    @Override
    public DifferentialFunction diff(Variable i_v) {
        return new Zero(m_factory);
    }

    @Override
    public String toString() {
        return getValue().toString();
    }

    @Override
    public String getFormula(List> variables) {
        return getValue().toString();
    }

    @Override
    protected DifferentialFunction plused(DifferentialFunction i_v) {
        return i_v.isConstant() ? new Constant(i_v.getValue().plus(this.m_x), m_factory)
                : super.plused(i_v);
    }

    @Override
    protected DifferentialFunction muled(DifferentialFunction i_v) {
        return i_v.isConstant() ? new Constant(i_v.getValue().mul(this.m_x), m_factory)
                : super.muled(i_v);
    }

    // public DifferentialFunction inverse() {
    @Override
    public Constant inverse() {
        return new Constant(m_x.inverse(), m_factory);
    }

    // public DifferentialFunction negate() {
    @Override
    public Constant negate() {
        return new Constant(m_x.negate(), m_factory);
    }

    // This class must be immutable.
    // set and assign must not be implemented.
    @SuppressWarnings("unused")
    private final void set(X i_x) {
    }

    @SuppressWarnings("unused")
    private final void assign(X i_x) {
    }

}