@Override
    public List<TensorFunction<NAMETYPE>> arguments() { return List.of(arg1, arg2); }
Convenience for cosine similarity between vectors.
cosine_similarity(a, b, mydim) == sum(a*b, mydim) / sqrt(sum(a*a, mydim) * sum(b*b, mydim)).

@author arnej
vespajlib/src/main/java/com/yahoo/tensor/functions/CosineSimilarity.java