代表的な活性化関数の例

import numpy as np
import matplotlib.pyplot as plt
from scipy.special import erf

# x軸の値を用意
x = np.linspace(-5, 5, 200)

# 各活性化関数を定義
def sigmoid(x):
    return 1 / (1 + np.exp(-x))

def tanh(x):
    return np.tanh(x)

def relu(x):
    return np.maximum(0, x)

def leaky_relu(x, alpha=0.1):
    return np.where(x > 0, x, alpha * x)

def swish(x):
    return x * sigmoid(x)

def gelu(x):
    return 0.5 * x * (1 + erf(x / np.sqrt(2)))

# 計算
y_sigmoid = sigmoid(x)
y_tanh = tanh(x)
y_relu = relu(x)
y_leaky_relu = leaky_relu(x)
y_swish = swish(x)
y_gelu = gelu(x)

# プロット
plt.plot(x, y_sigmoid, label='Sigmoid')
plt.plot(x, y_tanh, label='Tanh')
plt.plot(x, y_relu, label='ReLU')
plt.plot(x, y_leaky_relu, label='Leaky ReLU')
plt.plot(x, y_swish, label='Swish')
plt.plot(x, y_gelu, label='GELU')

plt.xlabel('x')
plt.ylabel('f(x)')
plt.title('Activation Functions')
plt.legend()
plt.grid(True)
plt.show()