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ELU Activation

Activation Functions
Easy

The Exponential Linear Unit (ELU) is an activation function that pushes mean activations closer to zero, which speeds up learning. Unlike ReLU, ELU produces a smooth curve for negative inputs, reducing the impact of the vanishing gradient problem.

Given a list of values and a parameter alpha, apply the ELU activation to each element.

Formula

ELU(x)=xif x>0ELU(x) = x \quad \text{if } x > 0ELU(x)=xif x>0 ELU(x)=α⋅(ex−1)if x≤0ELU(x) = \alpha \cdot (e^x - 1) \quad \text{if } x \le 0ELU(x)=α⋅(ex−1)if x≤0

The parameter alpha controls the negative saturation value. As x approaches negative infinity, ELU(x) approaches -alpha.

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Examples

Input:

x = [1.0, -1.0, 0.0, 2.0, -0.5], alpha = 1.0

Output:

[1.0, -0.6321, 0.0, 2.0, -0.3935]

Positive values pass through unchanged. Negative values are mapped through alpha * (exp(x) - 1), approaching -alpha for very negative x.

Input:

x = [-1.0, -2.0, -3.0], alpha = 2.0

Output:

[-1.2642, -1.7293, -1.9004]

With alpha = 2.0 the negative saturation value doubles compared to alpha = 1.0.

Hint 1

Use math.exp(v) to compute the exponential. The boundary condition is at x = 0: for x > 0 return x, for x <= 0 return alpha * (exp(x) - 1).

Hint 2

When alpha = 0, all negative values map to 0 (similar to ReLU). When alpha = 1, the function is continuous and smooth at x = 0.

Requirements

  • Apply the ELU formula element-wise to each value in the input list
  • Use the alpha parameter for negative values
  • Return a list of floats with the same length as the input

Constraints

  • Input list has at least one element
  • alpha >= 0
  • Return a list of floats with the same length as input
  • Time limit: 300 ms
Try Similar Problems
Relu ActivationLeaky ReluSelu ActivationSigmoid NumpyGelu

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Case 1
Case 2

Accepts: array

Accepts: number

You must run your code first.
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ELU Activation

Activation Functions
Easy

The Exponential Linear Unit (ELU) is an activation function that pushes mean activations closer to zero, which speeds up learning. Unlike ReLU, ELU produces a smooth curve for negative inputs, reducing the impact of the vanishing gradient problem.

Given a list of values and a parameter alpha, apply the ELU activation to each element.

Formula

ELU(x)=xif x>0ELU(x) = x \quad \text{if } x > 0ELU(x)=xif x>0 ELU(x)=α⋅(ex−1)if x≤0ELU(x) = \alpha \cdot (e^x - 1) \quad \text{if } x \le 0ELU(x)=α⋅(ex−1)if x≤0

The parameter alpha controls the negative saturation value. As x approaches negative infinity, ELU(x) approaches -alpha.

Loading visualization...

Examples

Input:

x = [1.0, -1.0, 0.0, 2.0, -0.5], alpha = 1.0

Output:

[1.0, -0.6321, 0.0, 2.0, -0.3935]

Positive values pass through unchanged. Negative values are mapped through alpha * (exp(x) - 1), approaching -alpha for very negative x.

Input:

x = [-1.0, -2.0, -3.0], alpha = 2.0

Output:

[-1.2642, -1.7293, -1.9004]

With alpha = 2.0 the negative saturation value doubles compared to alpha = 1.0.

Hint 1

Use math.exp(v) to compute the exponential. The boundary condition is at x = 0: for x > 0 return x, for x <= 0 return alpha * (exp(x) - 1).

Hint 2

When alpha = 0, all negative values map to 0 (similar to ReLU). When alpha = 1, the function is continuous and smooth at x = 0.

Requirements

  • Apply the ELU formula element-wise to each value in the input list
  • Use the alpha parameter for negative values
  • Return a list of floats with the same length as the input

Constraints

  • Input list has at least one element
  • alpha >= 0
  • Return a list of floats with the same length as input
  • Time limit: 300 ms
Try Similar Problems
Relu ActivationLeaky ReluSelu ActivationSigmoid NumpyGelu

Sign in to take notes on this problem

Case 1
Case 2

Accepts: array

Accepts: number

You must run your code first.