# #28 Machine Learning Specialization [Course 1, Week 2, Lesson 2] | Summary and Q&A

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December 1, 2022
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DeepLearningAI
#28 Machine Learning Specialization [Course 1, Week 2, Lesson 2]

## TL;DR

Learn how to choose an appropriate learning rate for your model by analyzing the cost function and ensuring it consistently decreases during iterations.

## Key Insights

• ☠️ Using an inappropriate learning rate can hinder the convergence and efficiency of gradient descent.
• ☠️ Overshooting the minimum can occur if the learning rate is too large, while a small learning rate can cause slow convergence.
• ☠️ Testing a range of learning rates and observing the cost function plot can help identify an optimal learning rate.

## Transcript

your learning album will run much better with an appropriate choice of learning rate if it's too small it will run very slowly and if it's too large it may not even converge let's take a look at how you can choose a good learning rate for your model concretely if you plot the cost for a number of iterations and notice that the cost sometimes goes u... Read More

### Q: Why is it important to choose an appropriate learning rate?

The learning rate determines the step size in gradient descent and affects the efficiency and convergence of the learning algorithm. An inappropriate learning rate can lead to slow convergence or failure to converge at all.

### Q: How can I identify if the learning rate is too large?

If, during iterations, the cost function sometimes increases instead of consistently decreasing, it indicates that the learning rate may be too large. Overshooting the minimum results in diverging instead of converging.

### Q: How can a bug in the code affect the cost function during iterations?

If the code contains a mistake in updating the parameters using the learning rate, such as adding instead of subtracting the derivative term, the cost function may consistently increase during iterations and move away from the global minimum.

### Q: How can I debug an incorrect implementation of gradient descent?

One method is to set the learning rate (Alpha) to a very small value and check if the cost function decreases on every iteration. If it still increases occasionally, it indicates that there is a bug in the code.

## Summary & Key Takeaways

• Selecting the correct learning rate is crucial for efficient training of a learning algorithm.

• If the learning rate is too small, the model will converge slowly, while a large learning rate may prevent convergence.

• To choose a good learning rate, observe the cost function plot during iterations, and if it consistently increases or fluctuates, adjust the learning rate accordingly.