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Dense Layer Forward Pass

Compute the outputs of a fully connected layer of neurons with a choice of activation.

Ce que vous allez apprendre

  • Compute a full layer of neurons at once
  • Apply a chosen activation to each output
  • Organize weights as one row per neuron

Problème

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A dense layer is a group of neurons that all receive the same inputs. Neuron j has its own weights weights[j] and bias biases[j]:

z_j = inputs · weights[j] + biases[j]

Then the layer's activation is applied to each z_j:

  • "linear": output z_j unchanged
  • "relu": max(0, z_j)
  • "sigmoid": 1 / (1 + e^(-z_j))

Implement dense_forward(inputs, weights, biases, activation).

Input

inputs: The n input values.

weights: One row per neuron; each row has n weights.

biases: One bias per neuron.

activation: "linear", "relu" or "sigmoid".

Output

Return the list of outputs, one per neuron, in order.

Contraintes

1 ≤ n ≤ 100, 1 ≤ number of neurons ≤ 100

-10 ≤ each value ≤ 10

Exemples

Exemple 1
Entrée :
biases = [0.0, -1.0]
inputs = [1.0, 2.0]
weights = [
    [0.5, -1.0],
    [1.5, 0.5]
]
activation = "relu"

Sortie attendue :
expected = [0.0, 1.5]
Entrée :
std::vector<double> biases = {0.0, -1.0};
std::vector<double> inputs = {1.0, 2.0};
std::vector<std::vector<double>> weights = {
    {0.5, -1.0},
    {1.5, 0.5}
};
std::string activation = "relu";

Sortie attendue :
std::vector<double> expected = {0.0, 1.5};
Entrée :
double[] biases = new double[] {0.0, -1.0};
double[] inputs = new double[] {1.0, 2.0};
double[][] weights = new double[][] {
    new double[] {0.5, -1.0},
    new double[] {1.5, 0.5}
};
string activation = "relu";

Sortie attendue :
double[] expected = new double[] {0.0, 1.5};

Explication

Neuron 1: 1×0.5 + 2×(-1) + 0 = -1.5, and ReLU gives 0. Neuron 2: 1×1.5 + 2×0.5 - 1 = 1.5, which ReLU keeps. Result: [0, 1.5].

Exemple 2
Entrée :
biases = [1.0, 0.0, -1.5]
inputs = [3.0]
weights = [
    [2.0],
    [-1.0],
    [0.5]
]
activation = "linear"

Sortie attendue :
expected = [7.0, -3.0, 0.0]
Entrée :
std::vector<double> biases = {1.0, 0.0, -1.5};
std::vector<double> inputs = {3.0};
std::vector<std::vector<double>> weights = {
    {2.0},
    {-1.0},
    {0.5}
};
std::string activation = "linear";

Sortie attendue :
std::vector<double> expected = {7.0, -3.0, 0.0};
Entrée :
double[] biases = new double[] {1.0, 0.0, -1.5};
double[] inputs = new double[] {3.0};
double[][] weights = new double[][] {
    new double[] {2.0},
    new double[] {-1.0},
    new double[] {0.5}
};
string activation = "linear";

Sortie attendue :
double[] expected = new double[] {7.0, -3.0, 0.0};

Explication

With a linear activation the outputs are just 3×2 + 1 = 7, 3×(-1) + 0 = -3 and 3×0.5 - 1.5 = 0.

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