use super::NormError;
pub fn layer_norm_in_place(
x: &mut [f32],
gamma: &[f32],
beta: &[f32],
eps: f32,
) -> Result<(), NormError> {
if x.is_empty() {
return Err(NormError::Empty);
}
if gamma.len() != x.len() || beta.len() != x.len() {
return Err(NormError::ShapeMismatch);
}
if !eps.is_finite() || eps <= 0.0 {
return Err(NormError::InvalidEps);
}
let mean = x.iter().copied().sum::<f32>() / x.len() as f32;
let mut var = 0.0f32;
for v in x.iter() {
let d = *v - mean;
var += d * d;
}
var /= x.len() as f32;
let inv_std = 1.0 / crate::math::sqrtf(var + eps);
for i in 0..x.len() {
let n = (x[i] - mean) * inv_std;
x[i] = n * gamma[i] + beta[i];
}
Ok(())
}
pub fn layer_norm(
input: &[f32],
gamma: &[f32],
beta: &[f32],
eps: f32,
out: &mut [f32],
) -> Result<(), NormError> {
if out.len() != input.len() {
return Err(NormError::ShapeMismatch);
}
out.copy_from_slice(input);
layer_norm_in_place(out, gamma, beta, eps)
}