diff --git a/av-variance.c b/av-variance.c
index 7a0b8f8..bc314aa 100644
--- a/av-variance.c
+++ b/av-variance.c
@@ -2,6 +2,7 @@
 #include <stdbool.h>
 #include <assert.h>
 #include <math.h>
+#include <values.h>
 
 double mean(double set[], int set_n) {
   double sum = 0.0;
@@ -35,6 +36,30 @@ double sample_stddev(double set[], int set_n) {
   return sqrt(sample_variance(set, set_n));
 }
 
+double set_min(double set[], int set_n) {
+  double min = MAXDOUBLE;
+
+  for(int i=0; i<set_n; i++) {
+    min=fmin(set[i], min);
+  }
+
+  return min;
+}
+
+double set_max(double set[], int set_n) {
+  double max = MINDOUBLE;
+
+  for (int i=0; i<set_n; i++) {
+    max=fmax(set[i], max);
+  }
+
+  return max;
+}
+
+double range(double set[], int set_n) {
+  return set_max(set, set_n) - set_min(set, set_n);
+}
+
 int main() {
   // Some data
   double d[] = {7, 8, 5, 1, 6, 2};
@@ -56,7 +81,14 @@ int main() {
   assert(isalmost(sample_stddev(d, d_n), 2.787, 0.001));
   assert(isalmost(sample_stddev(e, e_n), 6.447, 0.001));
 
-  // XXX Range
+  assert(isalmost(set_min(d, d_n),   1.0, 0.001));
+  assert(isalmost(set_max(d, d_n),   8.0, 0.001));
+  assert(isalmost(set_min(e, e_n), -10.0, 0.001));
+  assert(isalmost(set_max(e, e_n), +14.0, 0.001));
+
+  assert(isalmost(range(d, d_n),  7.0, 0.001));
+  assert(isalmost(range(e, e_n), 24.0, 0.001));
+
   // XXX Mode
   // XXX Percentile
 }