diff --git a/sm2.go b/sm2.go
new file mode 100644
index 0000000..05fd1cf
--- /dev/null
+++ b/sm2.go
@@ -0,0 +1,30 @@
+package main
+
+func SM2Next(thisGrade int, consecutivePassesBeforeThis int, ef float64, lastInterval int) (int, float64, int) {
+	q := thisGrade
+	n := consecutivePassesBeforeThis
+	ef = ef
+	i := lastInterval
+
+	if q >= 3 {
+		switch n {
+		case 0:
+			i = 1
+		case 1:
+			i = 6
+		default:
+			i = int(float64(i) * ef)
+		}
+		n += 1
+	} else {
+		n = 0
+		i = 1
+	}
+
+	ef = ef + (.1 - (5.0-float64(q))*(.08+(5.0-float64(q))*.02))
+	if ef < 1.3 {
+		ef = 1.3
+	}
+
+	return n, ef, i
+}