nexus-memory-core 1.2.5

Core types, traits, and business logic for Nexus Memory System
Documentation 
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/// Compute cosine similarity between two vectors.
///
/// Returns a value clamped to [0.0, 1.0]. This is intentional for embedding
/// similarity where negative values indicate orthogonal/anti-correlated vectors
/// and are treated as zero similarity for ranking purposes.
/// For the true mathematical range [-1.0, 1.0], use `cosine_similarity_raw`.
pub fn cosine_similarity(a: &[f32], b: &[f32]) -> f32 {
    if a.len() != b.len() || a.is_empty() {
        return 0.0;
    }
    let dot: f32 = a.iter().zip(b.iter()).map(|(x, y)| x * y).sum();
    let norm_a: f32 = a.iter().map(|x| x * x).sum::<f32>().sqrt();
    let norm_b: f32 = b.iter().map(|x| x * x).sum::<f32>().sqrt();
    if norm_a == 0.0 || norm_b == 0.0 {
        return 0.0;
    }
    (dot / (norm_a * norm_b)).clamp(0.0, 1.0)
}

/// Compute raw cosine similarity returning the true mathematical range [-1.0, 1.0].
pub fn cosine_similarity_raw(a: &[f32], b: &[f32]) -> f32 {
    if a.len() != b.len() || a.is_empty() {
        return 0.0;
    }
    let dot: f32 = a.iter().zip(b.iter()).map(|(x, y)| x * y).sum();
    let norm_a: f32 = a.iter().map(|x| x * x).sum::<f32>().sqrt();
    let norm_b: f32 = b.iter().map(|x| x * x).sum::<f32>().sqrt();
    if norm_a == 0.0 || norm_b == 0.0 {
        return 0.0;
    }
    dot / (norm_a * norm_b)
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_cosine_similarity_identical() {
        let v = [1.0, 2.0, 3.0];
        assert!((cosine_similarity(&v, &v) - 1.0).abs() < 1e-6);
    }

    #[test]
    fn test_cosine_similarity_orthogonal() {
        let a = [1.0, 0.0];
        let b = [0.0, 1.0];
        assert!((cosine_similarity(&a, &b) - 0.0).abs() < 1e-6);
    }

    #[test]
    fn test_cosine_similarity_empty() {
        assert_eq!(cosine_similarity(&[], &[]), 0.0);
    }

    #[test]
    fn test_cosine_similarity_mismatched_lengths() {
        assert_eq!(cosine_similarity(&[1.0], &[1.0, 2.0]), 0.0);
    }
}