1 files changed, 22 insertions, 0 deletions
diff --git a/src/lib/math/stats.h b/src/lib/math/stats.h
new file mode 100644
index 0000000000..328d61a9d6
--- /dev/null
+++ b/src/lib/math/stats.h
@@ -0,0 +1,22 @@
+/* Copyright (c) 2022, The Tor Project, Inc. */
+/* See LICENSE for licensing information */
+
+/**
+ * \file stats.h
+ *
+ * \brief Header for stats.c
+ **/
+
+#ifndef TOR_STATS_H
+#define TOR_STATS_H
+
+/** Update an average making it a "running average". The "avg" is the current
+ * value that will be updated to the new one. The "value" is the new value to
+ * add to the average and "n" is the new count as in including the "value". */
+static inline double
+stats_update_running_avg(double avg, double value, double n)
+{
+  return ((avg * (n - 1)) + value) / n;
+}
+
+#endif /* !defined(TOR_STATS_H) */