+#ifndef MEAN_H
+#define MEAN_H
+
+void mean_accumulate(entity e, .float a, .float c, float mean, float value, float weight)
+{
+ if (weight == 0)
+ return;
+ if (mean == 0)
+ e.(a) *= pow(value, weight);
+ else
+ e.(a) += pow(value, mean) * weight;
+ e.(c) += weight;
+}
+
+float mean_evaluate(entity e, .float a, .float c, float mean)
+{
+ if (e.(c) == 0)
+ return 0;
+ if (mean == 0)
+ return pow(e.(a), 1.0 / e.(c));
+ else
+ return pow(e.(a) / e.(c), 1.0 / mean);
+}
+
+#define MEAN_ACCUMULATE(prefix,v,w) mean_accumulate(self,prefix##_accumulator,prefix##_count,prefix##_mean,v,w)
+#define MEAN_EVALUATE(prefix) mean_evaluate(self,prefix##_accumulator,prefix##_count,prefix##_mean)
+#define MEAN_DECLARE(prefix,m) float prefix##_mean = m; .float prefix##_count, prefix##_accumulator
+
+#endif