use std::f64;
use activation::Activation;
#[derive(Copy, Clone)]
pub struct SoftPlus;
impl SoftPlus {
pub fn new() -> SoftPlus {
return SoftPlus;
}
}
impl Activation for SoftPlus {
fn calc(&self, x: Vec<f64>) -> Vec<f64> {
x.iter().map(|n| (1f64 + n.exp()).ln()).collect::<Vec<_>>()
}
fn derivative(&self, x: Vec<f64>) -> Vec<f64> {
x.iter()
.map(|n| 1f64 / (1f64 + (-n).exp()))
.collect::<Vec<_>>()
}
}
#[cfg(test)]
mod tests {
use super::Activation;
use super::SoftPlus;
#[test]
fn softplus_test() {
let activation = SoftPlus::new();
assert_approx_eq!(activation.calc(vec![-1f64])[0], 0.3132616875f64);
}
#[test]
fn softplus_derivative_test() {
let activation = SoftPlus::new();
assert_approx_eq!(activation.derivative(vec![-1f64])[0], 0.2689414214f64);
}
}