2015 経済動学 講義資料 (2015-05-18)

2015-05-18.ipynb

duck.py

import numpy as np

class System:
	def __init__(self, f, dim):
		self.f = f
		self.dim = dim

	def forward(self, x):
		return self.f(x)

def simulate(s, *, start, steps):

	x = np.array(start)
	count = 0

	while count < steps:
		yield x
		x = s.forward(x)
		count += 1


def shoot(s, *, goal, steps):

	for 


if __name__ == "__main__":

	def f(x):
		A = np.array([[1.0, -0.5], [0.0, 1.0]])
		return np.dot(A, x)

	s = System(f, (2, 2))

	path = simulate(s, start=[1., 1.], steps=10)

klass.py

import numpy as np

class System:
    def __init__(self, dim):
        self.dim = dim
        
    def forward(self, x):
        pass
        
class Logistic(System):
    def __init__(self, a):
        self.a = a
        super().__init__(dim=1)
        # System.__init__(dim=1)
        
    def forward(self, x):
        return self.a * x * (1 - x)
    
class Tent(System):
    def __init__(self, a):
        self.a = a
        super().__init__(dim=1)
        
    def forward(self, x):
        return self.a * min(x, 1 - x)
    

class Linear(System):
    def __init__(self, A):
        self.A = A
        super().__init__(dim=A.shape[0])
    
    def forward(self, x):
        return np.dot(self.A, x)

class NoUse:
    def forward(self, x):
        return 2 * x     
        
def run(system, x, steps):
    for i in range(steps):
        x1 = system.forward(x)
        yield x
        x = x1
        
        
        
        
        

note.py

# Generators

def logistic(x):
    """Logistic map"""
    return 4 * x * (1 - x)
    
def logistic_path(x, length):
    y = [x]
    for _ in range(length - 1):
        y.append(logistic(y[-1]))
    return y

def logistic_gen(x, length):
    for _ in range(length):
        x1 = logistic(x)
        yield x
        x = x1