5个f语言有限差分正演程序，应用有限差分法在CPML边界条件下进行2D正演，前四个程序分别对应各向异性介质、各项同性2阶精度、各项同性4阶精度、双相介质4阶精度四种不同情况。最后一个是3D粘弹性介质的程序。-5 f language finite difference modeling, application of finite difference method under CPML boundary conditions 2D forward, the first four program