/**
 * Compute cosine similarity between two vectors.
 * Returns a value in [0, 1] where 1 means identical direction.
 */
export declare function cosineSimilarity(a: number[], b: number[]): number;
/**
 * Compute Jaccard similarity between two binary-ish vectors.
 * Treats non-zero values as "present". Returns value in [0, 1].
 */
export declare function jaccardSimilarity(a: number[], b: number[]): number;
/**
 * Combined similarity: weighted average of cosine and jaccard.
 * Default weights: 0.8 cosine + 0.2 jaccard.
 */
export declare function combinedSimilarity(a: number[], b: number[], cosineWeight?: number): number;
/**
 * Normalize a vector to unit length (L2 norm).
 * Returns a new array. If the vector is zero, returns a zero vector.
 */
export declare function normalizeVector(v: number[]): number[];
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