The Modern Mathematics of Deep Learningexplained for non-mathematicians

Polynomial feature vector

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.

Features · Transform inputs into features used by a rule.

The project scales bill and flipper measurements using training-row means and scales; its feature vector has two entries.

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: 1.3 The questions ahead

The feature vector lists the constant 1 and powers of Z through Zᵈ.

These features permit a linear model in the features to express a polynomial in Z.

Source formula example

X=(1,Z,…,Zd)X=(1,Z,\dots,Z^{d})

illustration · This evaluates a feature map for one value of Z; Z can be random in the source.

Symbols

ZZ
A scalar input.
dd
The nonnegative integer degree.
XX
A vector of d+1 polynomial features.

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

  • Z = 2
  • d = 3

Calculated here

Result expression: { Z, d, X }

  • X = Array.from({ length: d + 1 }, (_, i) => Z ** i) Uses: d, Z

Returns

Example result
Z
2
d
3
X
array (4 items): [1, 2, 4, 8]

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 evaluates a feature map for one value of Z; Z can be random in the source.

Source: Inline notation