strgrp: Use angular similarity for distance metric properties

[ccan] / ccan / strgrp / strgrp.c

diff --git a/ccan/strgrp/strgrp.c b/ccan/strgrp/strgrp.c
index 111e592edb8920cb5a9c27ea184d6d97be98d0ff..12119a1f276c7e4c4a9776cf061d1b8dfc77eddf 100644 (file)
--- a/ccan/strgrp/strgrp.c
+++ b/ccan/strgrp/strgrp.c
@@ -103,7 +103,7 @@ strcossim(const int16_t ref[CHAR_N_VALUES], const int16_t key[CHAR_N_VALUES]) {
         sai2 += ref[i] * ref[i];
         sbi2 += key[i] * key[i];
     }
-    return saibi / (sqrt(sai2) * sqrt(sbi2));
+    return 1.0 - (2 * acos(saibi / sqrt(sai2 * sbi2)) / M_PI);
 }
 
 /* Low-cost filter functions */