A step of the mafft_native implementation. Called by find_homologous_segments,
mafft_nw.
See the file header for the source the module follows.
Examples
sc <- normalized_similarity_matrix(seq_type = "aa")
mafft_site_score(sc$M, list("MKV"), list("MRV"), 1, 1, 2L, 2L)
#> [1] 0
