Affine Map
A linear model used in deep learning is often an affine map.
For one output score:
score = x . w + b
The dot product x . w is a weighted sum. The bias b shifts the result.
Suppose:
x = [2, 3]
w = [4, -1]
b = 5
Then:
score = 2 x 4 + 3 x (-1) + 5
= 8 - 3 + 5
= 10
The score is not yet a probability. It is a raw number produced by the model.
DL-C03-T01-001Exercise: Compute one score
Let x = [1, 4], w = [3, -2], and b = 5. Compute x . w + b.
Compute it first, then check your number.
HintUse weighted sum plus bias
Compute 1 x 3 + 4 x (-2) + 5.
SolutionWork it out
1 x 3 + 4 x (-2) + 5 = 3 - 8 + 5 = 0.
DL-C03-T01-002Exercise: Is it a probability
A model returns score 3.7. Enter 1 if this raw score is already a probability, or 0 if it is not necessarily a probability.
Compute it first, then check your number.
HintCheck the range
Probabilities must stay between 0 and 1.
SolutionWork it out
A raw score can be any real number. Since 3.7 is greater than 1, it is
not a probability.