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Meta·Machine Learning Engineer·Technical Phone Screen·Intermediate

IntermediatePrefer not to say
Jun 2026

Summary

Interviewed at Meta for what seemed like a machine learning or data science adjacent role. One question, pretty fundamental, but I still managed to fumble parts of it.

Questions Asked (1)

Q1

Can you explain how gradient descent works?

Technical Trade-offsAlgorithms & Data Structures
Author's notes

I knew this cold, or thought I did.

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AI HintsAI Generated

Suggested Approach

Start with a clear, intuitive explanation of gradient descent as an optimization algorithm that iteratively adjusts parameters to minimize a loss function. Then, formalize it with the update rule and discuss key variants and practical considerations. Finally, connect it to real-world ML applications, especially at scale, to show depth.

Pro tip: Mention that while gradient descent is foundational, its variants like Adam or SGD with momentum are often preferred in practice due to faster convergence and robustness to hyperparameters. Also, briefly touch on challenges like local minima and saddle points in high-dimensional spaces.

1. Intuitive Explanation

Describe gradient descent as a way to find the minimum of a function by taking steps proportional to the negative of the gradient. Use the analogy of descending a hill.

2. Mathematical Formulation

Present the update rule: θ = θ - η * ∇J(θ), where η is the learning rate and ∇J(θ) is the gradient of the loss function. Explain each term.

3. Variants and Trade-offs

Discuss batch, stochastic, and mini-batch gradient descent, highlighting their pros and cons in terms of computational efficiency and convergence stability.

4. Practical Considerations

Mention learning rate selection, convergence criteria, and common optimizers like Momentum, RMSProp, and Adam. Briefly touch on challenges like local minima and saddle points.

5. Application at Scale

Relate to large-scale ML at companies like Meta, emphasizing distributed training and the need for efficient variants like asynchronous SGD.

Key Points to Mention

  • Definition of gradient descent and its role in minimizing loss functions
  • The update rule and the importance of the learning rate
  • Variants: batch, stochastic, and mini-batch gradient descent
  • Common optimizers: Momentum, RMSProp, Adam
  • Challenges: local minima, saddle points, and learning rate tuning
  • Scalability: distributed and asynchronous SGD for large datasets

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.