创建型模式 简单工厂模式(2)

实现数学运算 快速傅里叶变换

其中 Complex是实体类

using System;

namespace FFT
{
    /**//// <summary>
    /// Summary description for Complex.
    /// </summary>
    public class Complex
    {
            float real;
            float imag;
       //---------------------------------
            public Complex(float r, float i) {
                real = r;                              
                imag = i;
            }
        //---------------------------------
        public void setReal(float r) {
            real = r;
        }
        //---------------------------------
        public void setImag(float i) {
            imag= i;
        }
        //---------------------------------
        public float getReal() {
            return real;
        }
        //---------------------------------
        public float getImag() {
            return imag;
        }

        
    }
}

Cocoon用来选择对那个类进行事例化

using System;

namespace FFT
{
    /**//// <summary>
    /// Summary description for Cocoon.
    /// </summary>
    public class Cocoon     {
        static public Butterfly getButterfly(float y) {
            if (y != 0)
                return new TrigButterfly(y);
            else
                return new addButterfly(y);
        }
    }
}

其中TrigButterfly和addButterfly都继承Butterfly

using System;

namespace FFT
{
    /**//// <summary>
    /// Summary description for TrigButterfly.
    /// </summary>
    public class TrigButterfly:Butterfly
    {
        float y;
        float oldr1, oldi1;
        float cosy, siny;
        float r2cosy, r2siny, i2cosy, i2siny;
   
        public TrigButterfly(float angle) {
            y = angle;
            cosy = (float) Math.Cos(y);
            siny = (float)Math.Sin(y);
 
        }
        public override void Execute(Complex xi, Complex xj) {
            oldr1 = xi.getReal();
            oldi1 = xi.getImag();
            r2cosy = xj.getReal() * cosy;
            r2siny = xj.getReal() * siny;
            i2cosy = xj.getImag()*cosy;
            i2siny = xj.getImag()*siny;
            xi.setReal(oldr1 + r2cosy +i2siny);
            xi.setImag(oldi1 - r2siny +i2cosy);
            xj.setReal(oldr1 - r2cosy - i2siny);
            xj.setImag(oldi1 + r2siny - i2cosy);  
        }

    }
}

using System;

namespace FFT
{
    /**//// <summary>
    /// Summary description for AddButterfly.
    /// </summary>
    class addButterfly : Butterfly 
    {
       float oldr1, oldi1;

        public addButterfly(float angle) {
        }
        public override void Execute(Complex xi, Complex xj) {
            oldr1 = xi.getReal();
            oldi1 = xi.getImag();
            xi.setReal(oldr1 + xj.getReal());
            xj.setReal(oldr1 - xj.getReal());
            xi.setImag(oldi1 + xj.getImag());
            xj.setImag(oldi1 - xj.getImag());
        }
    }

}

using System;

namespace FFT
{
    /**//// <summary>
    ///Computes the complex multiplications for the FFT
    /// </summary>
    public abstract class Butterfly
    {
            float y;
            public Butterfly() {
            }
            public Butterfly(float angle) {
                y = angle;
            }
            abstract public void Execute(Complex x, Complex y);
    }
}

其中Butterfly是抽象类，
abstract public void Execute(Complex x, Complex y);
是抽象方法