for j := 0.0; j < mass; j += mass * 0.099 {
			mud.setTrackMass(j)
			l, u, ok := mud.approxInvCumulativeSum()
			inv, ok2 := mud.invCumulativeSum(j)
			if !ok || !ok2 {
				t.Fatalf("inverse cumulative sum failed: approx %v, exact %v", ok, ok2)
			}
			if !(l <= inv && inv < u) {
				t.Fatalf("inverse(%g) = %g, not ∈ [%g, %g)", j, inv, l, u)
			}
		}
	}
}

func TestMUDTracking(t *testing.T) {

		t.Error("unexpected output for inv(1)")
	}
	new(big.Int).Add(N, big.NewInt(1)).FillBytes(input)
	out, err = nistec.P256OrdInverse(input)
	if err != nil {
		t.Fatal(err)
	}
	if !bytes.Equal(out, exp) {
		t.Error("unexpected output for inv(N+1)")
	}

	// Check inv(20) and inv(N+20) against math/big
	exp = new(big.Int).ModInverse(big.NewInt(20), N).FillBytes(make([]byte, 32))
	big.NewInt(20).FillBytes(input)

    for (Entry<K, V> entry : entries) {
      Entry<V, K> reversed = reverseEntry(entry);
      BiMap<V, K> inv = getMap().inverse();
      assertFalse(
          "Inverse should not contain entry " + reversed, inv.entrySet().contains(reversed));
      assertFalse(
          "Inverse should not contain key " + reversed.getKey(),
          inv.containsKey(reversed.getKey()));
      assertFalse(

    for (Entry<K, V> entry : entries) {
      Entry<V, K> reversed = reverseEntry(entry);
      BiMap<V, K> inv = getMap().inverse();
      assertFalse(
          "Inverse should not contain entry " + reversed, inv.entrySet().contains(reversed));
      assertFalse(
          "Inverse should not contain key " + reversed.getKey(),
          inv.containsKey(reversed.getKey()));
      assertFalse(