Quiz 2

Gradient Descent and Optimization

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Python Week 1: the first filter for runtime behavior
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# Gradient Descent and Optimization ## 4.1 Gradient Descent $$ \boldsymbol{\beta}^{(t+1)} = \boldsymbol{\beta}^{(t)} - \eta \nabla L(\boldsymbol{\beta}^{(t)}) $$ ## 4.2 Stochastic Gradient Descent Update using a single observation at a time — much faster for large datasets. ## 4.3 Newton-Raphson $$ \boldsymbol{\beta...

Gradient Descent and Optimization

4.1 Gradient Descent

β(t+1)=β(t)ηL(β(t))\boldsymbol{\beta}^{(t+1)} = \boldsymbol{\beta}^{(t)} - \eta \nabla L(\boldsymbol{\beta}^{(t)})
python
import numpy as np
def gradient_descent(X, y, lr=0.01, epochs=1000):
    n, p = X.shape
    beta = np.zeros(p)
    for epoch in range(epochs):
        grad = -2/n * X.T @ (y - X @ beta)
        beta -= lr * grad
    return beta

4.2 Stochastic Gradient Descent

Update using a single observation at a time — much faster for large datasets.

4.3 Newton-Raphson

β(t+1)=β(t)H1L(β(t))\boldsymbol{\beta}^{(t+1)} = \boldsymbol{\beta}^{(t)} - \mathbf{H}^{-1} \nabla L(\boldsymbol{\beta}^{(t)})
Where H\mathbf{H} is the Hessian matrix. Faster convergence but O(p3)O(p^3) per iteration. Join Discord PreviousCross-ValidationNextSGD Variants
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