Gradient Checking Implementation Notes (C2W1L14)  Summary and Q&A
TL;DR
Implementing gradient checking requires using backprop to compute the derivative, identifying bugs by comparing individual components, considering regularization terms, and accounting for dropout.
Key Insights
 đąī¸ Use backprop instead of gradient descent for computing the derivative in neural networks.
 đ To identify bugs, compare individual components of D theta and D theta aprox.
 đ Regularization terms should be included when performing gradient checking with neural networks.
 đģ Gradient checking is not suitable for dropout due to the difficulty of computing the cost function accurately.
 âŠī¸ It is recommended to turn off dropout during gradient checking to ensure correct implementation.
 đī¸ Implementing gradient descent may have different accuracy levels depending on the magnitude of the weights.
 đ One can run gradient checking after training the network for a while to ensure accurate calculations for larger weights.
Transcript
in the last video you learned about gradient checking in this video I want to share you some practical tips or some notes on how to actually go about implementing this for your neural network first don't use graduating training or me to debug so what I mean is that computing D theta or procs eyes all the values of ID is a very slow computation so t... Read More
Questions & Answers
Q: Why should backprop be used to compute the derivative instead of gradient descent?
Backprop is more efficient than gradient descent for computing the derivative and should be used during the implementation process. Gradient descent is only necessary when debugging.
Q: How can individual component comparisons help identify bugs?
By comparing the values of D theta and D theta aprox for different components, you can identify which components are causing the discrepancy. This can help narrow down the location of the bug.
Q: What should be considered when performing gradient checking with regularization?
The regularization term should be included in the cost function when calculating the gradient. It is important to ensure that D theta includes the gradients of both the loss function and the regularization term.
Q: Why is gradient checking difficult to use with dropout?
Dropout eliminates different subsets of nodes in each iteration, making it challenging to compute a cost function. Gradient checking relies on computing the cost function accurately, which is not straightforward with dropout.
Summary & Key Takeaways

To implement gradient descent, use backprop to compute the derivative, except when debugging.

When the gradient check fails, compare individual components to identify the bug.

Remember to include the regularization term when performing gradient checking.

Gradient checking does not work well with dropout, so it is recommended to turn off dropout during the checking process.