# Computation Graph (C1W2L07) | Summary and Q&A

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August 25, 2017
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DeepLearningAI
Computation Graph (C1W2L07)

## TL;DR

Computation graphs explain the organization of computations in neural networks, with forward and backward passes playing key roles.

## Key Insights

• đ§­ Computation graphs organize computations in neural networks, with a forward pass for output computation and a backward pass for gradient computation.
• đģ The example of computing a function with three variables demonstrates the step-wise calculation involved.
• đ Optimization of output variables, such as minimizing the cost function in logistic regression, benefits from computation graphs.
• đ¯ī¸ Left-to-right passes compute output values, while right-to-left passes are useful for computing derivatives.
• đ Computation graphs help visualize the flow and dependencies of computations in neural networks.
• â Backpropagation enables efficient computation of derivatives, contributing to efficient neural network training.
• đĻģ Computation graphs aid in understanding the organization and optimization of neural network computations.

## Transcript

probably say that the computations of a neural network are all organized in terms of a forward path or a forward propagation step in which we compute the output of the new network followed by a backward pass or a back complication step which we use to compute gradients or compute derivatives the computation graph explains why it is organized this w... Read More

### Q: How are the computations in a neural network organized?

The computations in a neural network are organized into a forward pass and a backward pass. The forward pass calculates the output of the network, while the backward pass computes gradients or derivatives.

### Q: How is a computation graph useful?

A computation graph visually represents the steps involved in computing a function. It helps understand the flow of computations and is particularly useful when optimizing a specific output variable.

### Q: What is the purpose of backpropagation in neural networks?

Backpropagation, or the backward pass, is used to compute derivatives of the output variable with respect to the input variables. It allows for efficient computation of gradients, enabling neural network training.

### Q: How is a computation graph helpful in understanding logistic regression?

In logistic regression, the cost function (J) is the output variable that needs to be minimized. The computation graph helps compute the value of J in a left-to-right pass and derivatives in a right-to-left pass.

## Summary & Key Takeaways

• The computations in a neural network are organized into a forward pass and a backward pass, also known as forward propagation and backpropagation.

• A computation graph helps illustrate these steps, using a simple example of computing a function with three variables.

• The graph shows how each step is connected, from computing u to calculating v and finally obtaining the output J.