How can I choose function with class fuction?-CodePudding

class ODEsolver():
    def __init__(self):
        self.init=self
  def Euler(self, fcn, x0, y0, xend, h):
    estimate=[y0]
    z=y0
    b=0
    t=x0   
    while(t<xend):
      slope1=fnc(bisection(t,301,1200,10**-4))
      y=z slope1*h/8
      t =h
      z=y
      estimate.append(y)
    return estimate

    def Heun(self, fcn, x0, y0, xend, h):
    def RungeKutta(self,fcn,x0,y0,xend,h):

    def solve(self,which, fcn, x0, y0, xend, h):
        if which==0:
            self.Euler(fcn,x0,y0,xend,h)
        elif which==1:
            self.Heun(fcn,x0,y0,xend,h)
        else:
            self.RungeKutta(fcn,x0,y0,xend,h)

I'm trying to choose function and get return as list([]). But e=r.solve(0,diff,0,1200,6000,30) returns NONE. How can I get right return from this code?

*I simplified other functions such as Heun,RungeKutta because I noticed the problem is in r.solve() because simply calling function like r.Euler worked well.

CodePudding user response：

You can use getattr.

Like this:

def solve(self, which, fcn, x0, y0, xend, h):
    fn = getattr(self, which)
    return fn(fcn, x0, y0, xend, h)

... and then pass the desired method name as the argument:

solver = ODEsolver()
return solver.solve('Euler', 42, 42, 42, 42, 100500)

CodePudding user response：

You aren't returning. You just invoked the Euler, Heun and RungeKutta functions. You have to return the answers, try to store the answer in a variable and return it on the end of the function, like this:

def solve(self,which, fcn, x0, y0, xend, h):
  if which==0:
    answer = self.Euler(fcn,x0,y0,xend,h)
  elif which==1:
    answer = self.Heun(fcn,x0,y0,xend,h)
  else:
    answer = self.RungeKutta(fcn,x0,y0,xend,h)
  return answer