nnrs 0.2.3

Rust Neural Network Library
Documentation 
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use serde::{Deserialize, Serialize};

/// Activation function for a neuron.
#[derive(Debug, Clone, Copy, PartialEq, Deserialize, Serialize)]
pub enum ActivationFn {
    /// `|x| x.max(0.0)`
    ReLU,

    /// `|x| 1.0 / (1.0 + (-x).exp())`
    Sigmoid,

    /// `|x| x.tanh()`
    Tanh,

    /// `|x|` x, aka do nothing
    Linear,

    /// `|x, threshold| if x > threshold { 1.0 } else { 0.0 }`
    Step(f64),
}

impl ActivationFn {
    pub(crate) fn run(&self, x: f64) -> f64 {
        match self {
            ActivationFn::ReLU => x.max(0.0),
            ActivationFn::Sigmoid => 1.0 / (1.0 + (-x).exp()),
            ActivationFn::Tanh => x.tanh(),
            ActivationFn::Linear => x,
            ActivationFn::Step(threshold) => {
                if x > *threshold {
                    1.0
                } else {
                    0.0
                }
            }
        }
    }
}