use cost::CostFunction;
use matrix::Matrix;
use matrix::MatrixTrait;
use cost::CostFunctions;
pub struct SquaredError;
impl SquaredError {
pub fn new() -> SquaredError {
SquaredError
}
}
impl CostFunction for SquaredError {
fn name(&self) -> CostFunctions {
CostFunctions::SquaredError
}
fn calc(&self, prediction: &Matrix, target: &Matrix) -> f64 {
let mut errors = Vec::with_capacity(prediction.cols());
for (i, p) in prediction.row(0).iter().enumerate() {
errors.push((target.get(0, i) - p).powi(2) / 2f64);
}
errors.iter().fold(0f64, |sum, val| sum + val)
}
}