递归下降，出四元式

例如:当输入(i+i*i)*(i+i)时,输出以下的四元式序列。

t1 := i * i

t2 := i + t1

t3 := i + i

t4 := t2 * t3

-Recursive descent, a quaternion type, for example: when the input (i+i* i)* (i+i), following output of the quaternion type sequence. t1: = i* i t2: = i+ t1 t3: = i+ i t4: = t2* t3