+ return _num_1.mul(lh);
+}
+
+
+// increment / decrement operators
+
+/** Expression prefix increment. Adds 1 and returns incremented ex. */
+ex & operator++(ex & rh)
+{
+ return rh = exadd(rh, _ex1);
+}
+
+/** Expression prefix decrement. Subtracts 1 and returns decremented ex. */
+ex & operator--(ex & rh)
+{
+ return rh = exadd(rh, _ex_1);
+}
+
+/** Expression postfix increment. Returns the ex and leaves the original
+ * incremented by 1. */
+const ex operator++(ex & lh, int)
+{
+ ex tmp(lh);
+ lh = exadd(lh, _ex1);
+ return tmp;
+}
+
+/** Expression postfix decrement. Returns the ex and leaves the original
+ * decremented by 1. */
+const ex operator--(ex & lh, int)
+{
+ ex tmp(lh);
+ lh = exadd(lh, _ex_1);
+ return tmp;