Question

为了解决一些微分值问题，我编写了一个类和一个步进器来计算二阶Runge-Kutta方法。我的问题是，如果我从一个类中调用此函数，则会出现错误，如果我由另一个步进器调用，则不会！

我在这里报告了很短的代码：这是类方法stepper：

@classmethod
def step(cls,func , t : np.float , u : np.float , dt ):

    def f(ti,ui):
        return  np.array([function(ti,ui) for function in func])     

    k1 = f(t,u)
    k2 = f(t+dt/2. , u + dt/2.*k1)

    unext = u + dt*k2       
    return unext

如果我使用它来解决微分问题，它将起作用……就像这种情况：

with open('RungeKutta2_p1.dat', 'w') as f:
        while True:
            f.write('%10.4f %10.4f \n' %(t, u[0]) )
            u = rungekutta.RK2.step(func0,t,u,dt)
            t += dt
            if t >= tf:
               break

如果我从另一个步进器中调用它：

t,u = t0,u0 
   with open('AdamsBashforth2_p1.dat', 'w') as f:
        while True:
            f.write('%10.4f %10.4f \n' %(t, u[0]) )
            u = adamsmethods.AdamsBashforth._2nd.step(func0,t,u,dt)
            t += dt
            if t >= tf:
               break

其中定义了adamsmethods.AdamsBashforth._2nd.step的地方：

   @classmethod
   def step(cls, func , t : np.float , u : np.float, dt ):

        def f(ti,ui):
            return  np.array([function(ti,ui) for function in func])     

        if cls.startup == False:
        #print ("AB start-up")
            AdamsBashforth._2nd.u1 = rungekutta.RK2.step(func,t,u,dt)
            AdamsBashforth._2nd.startup = True

        unext = AdamsBashforth._2nd.u1 + dt/2.*3.*f(t+dt,AdamsBashforth._2nd.u1) - f(t,u))
        AdamsBashforth._2nd.u1 = u

问题是当我尝试调用它以启动方法时：考虑这个课程：

class AdamsBashforth(AdamsMethods):

    def __init__(self, dydt, filename :str = None , save : bool = True):
        self._2nd = AdamsBashforth._2nd(dydt,filename,save)

    def solve(self):
        pass

    class _2nd(AdamsMethods):
           startup = False
           solved  = False 
           def __init__(self, dydt : Rhs, filename :str = None , save : bool = True ):
                self.file = filename
                self.save = save
                super().__init__(dydt)

           def solve(self):

                self.time , self.u = self.dydt.createArray()
                self.u[1] = rungekutta.RK2.step(self.dydt.f, self.time[0], self.u[0], self.dt)

                for i in range(1,len(self.time)-1):
                    self.u[i+1] = u[i] + self.dt/2*(3*self.dydt.f(self.time[i],self.u[i])-self.dydt.f(self.time[i-1],self.u[i-1]))

                _2nd.solved = True    

                if self.file != None:
                    super().write2file()

                if self.save:
                    return self.time,self.u

此处失败并显示此错误：

Traceback (most recent call last):
  File "drive.py", line 287, in <module>
    main()
  File "drive.py", line 225, in main
    ab2t,ab2u = ab2_p1._2nd.solve()
  File "/home/marco/Programming/Python/Numeric/OdeSystem/adamsmethods.py", line 46, in solve
    self.u[1] = rungekutta.RK2.step(self.dydt.f, self.time[0], self.u[0], self.dt)
  File "/home/marco/Programming/Python/Numeric/OdeSystem/rungekutta.py", line 100, in step
    k1 = f(t,u)
  File "/home/marco/Programming/Python/Numeric/OdeSystem/rungekutta.py", line 98, in f
    return  np.array([function(ti,ui) for function in func])     
TypeError: 'method' object is not iterable
------------------------------------------------------------

如果问题没有得到很好的解释，请告诉我，我给您所有进一步的信息！

编辑你是对的！！这是一个方法而不是np.array ...我该如何解决？我在通话之前尝试写这个：

def fn(ti,ui):
       return  np.array([function(ti,ui) for function in self.dydt.f])

但我收到此消息：

Traceback (most recent call last):
  File "drive.py", line 287, in <module>
    main()
  File "drive.py", line 225, in main
    ab2t,ab2u = ab2_p1._2nd.solve()
  File "/home/marco/Programming/Python/Numeric/OdeSystem/adamsmethods.py", line 51, in solve
    print(type(fn(self.time[0],self.u[0])))
  File "/home/marco/Programming/Python/Numeric/OdeSystem/adamsmethods.py", line 50, in fn
    return  np.array([function(ti,ui) for function in self.dydt.f])     
TypeError: 'method' object is not iterable
------------------------------------------------------------

classmethod在一种情况下不起作用，但在另一种情况下它起作用

0 个答案: