1 files changed, 4 insertions, 1 deletions
diff --git a/ot/utils.py b/ot/utils.py
index 8419c83..be839f8 100644
--- a/ot/utils.py
+++ b/ot/utils.py
@@ -186,7 +186,10 @@ def cost_normalization(C, norm=None):
         C = np.log(1 + C)
     elif norm == "loglog":
         C = np.log1p(np.log1p(C))
-
+    else:
+        raise ValueError(f'Norm {norm} is not a valid option. '
+                         f'Valid options are:\n'
+                         f'median, max, log, loglog')
     return C