The Modern Mathematics of Deep Learningexplained for non-mathematicians

Gaussian weight and bias initialization

Penguin learning project

The project uses 342 complete Palmer penguin records: 240 training-pool and 102 held-out rows. The selected training rows determine feature scaling and model parameters. Source CSV

This project trains weights with softmax, unlike the homepage lab, which uses nearest species averages. Same penguin measurements; different classification methods. Predictions can differ.

Initialization · Describe initial parameters and their distributions.

The current objective supplies a gradient; training updates the model parameters.

Consider this concept alongside the project; its source assumptions may differ. These observations do not prove a theorem.

Input: 12 × 2; Held-out evaluation: 102 · #58 · 40.6 mm, 193 mm. Known answer: Adélie; Prediction: Adélie · [≈0.7383, ≈0.2444, ≈0.01737].

Used in these source sections: 2.1 A view through similarity

For the ℓ-th layer, initial weights have mean zero and variance σw²/Nℓ; biases have mean zero and variance σb².

These values specify the normal initialization laws.

Source formula example

ℓ\ell

illustration · This gives the moments of the source normal laws; it does not draw values or establish convergence.

Symbols

ℓℓ
Layer index.
NℓNℓ
Layer width.
σw,σbσw,σb
Positive initialization scales.

Source formula example

This source example uses its own inputs and assumptions. Editing it does not change the project.

Edit a value or the code, then run the example. This is a finite demonstration, not a proof of the paper’s theorem.

This example’s data flow

Initial values in code

  • layer = 1
  • width = 4
  • sigmaW = 2
  • sigmaB = 1

Calculated here

Result expression: { layer, width, weightMean: 0, weightVariance: (sigmaW * sigmaW) / width, biasMean: 0, biasVariance: sigmaB * sigmaB, }

Returns

Example result
layer
1
width
4
weightMean
0
weightVariance
1
biasMean
0
biasVariance
1

Read numbers from input and return the result. JavaScript basics.

Result

Enable JavaScript to run this example.

Technical statement

The numerical values are invented. This gives the moments of the source normal laws; it does not draw values or establish convergence.

Source: Inline notation