下面是用户手册中简支梁的例子。请问怎样把梁的某个节点的位移以及某个单元的弯矩提取出来？如需要提取第4个节点的竖向位移和第5个单元的轴力。谢谢！
struct node 1 0.0,0.0
struct node 2 3.0,0.0
struct node 3 6.0,0.0
struct node 4 9.0,0.0
struct beam begin node 1 end node 2 seg 3 prop 1001
struct beam begin node 2 end node 3 seg 4 prop 1001
struct beam begin node 3 end node 4 seg 3 prop 1001
struct prop 1001 e 2.0E11 area 0.0060 I 2.0E-4
struct node 1 fix y
struct node 4 fix y
struct node 2 load 0.0,-10000.0 0.0
struct node 3 load 0.0,-10000.0 0.0
history 1 node 8 ydisplace
history 4 element 1 moment2
history 5 element 2 moment1
history 999 unbalanced
solve
