step function (계단 함수)
$$ h(x) = \begin{cases} 1 & (x > 0) \\ 0 & (x \leqq 0) \end{cases} $$
import numpy as np
def step_function(x):
return np.array(x > 0, dtype=np.int)
계단 함수의 그래프
import matplotlib.pylab as plt x = np.arange(-5.0, 5.0, 0.1) y = step_function(x) plt.plot(x, y) plt.ylim(-0.1, 1.1) plt.show()
sigmoid (시그모이드)
d
$$ h(x) = \frac{1}{1 + e^{-x}} $$
def sigmoid(x):
return 1 / (1 + np.exp(-x))
x = np.arange(-5.0, 5.0, 0.1) y = sigmoid(x) plt.plot(x, y) plt.ylim(-0.1, 1.1) plt.show()
dd
ReLU (Rectified Linear Unit, 렐루)
$$ h(x) = \begin{cases} x & (x > 0) \\ 0 & (x \leqq 0) \end{cases} $$
def relu(x):
return np.maximum(0, x)
x = np.arange(-5.0, 5.0, 0.1) y = relu(x) plt.plot(x, y) plt.ylim(-1.0, 5.0) plt.show()
