计算退磁曲线的Preisach模型，用matlab实现

此程序碼為preisach模型之解析法計算，其計算精度很高-This procedure code is preisach analytical model of the method, its high calculation accuracy

matlab实现Preisach模型，画出Everett函数以及Preisach平面-- approximate measured hysteresis loops - simulate arbitrary minor hysteresis loops - plot the Preisach function, the Everett function, the reversible component