求杆件微小位移 我好不容易弄好的
 

先save文件data.txt内容为2
-1 0 2.0e11 0.1
0 1 2.0e11 0.1
0 0
100 -100
运行：fid=fopen('data1.txt','rt');
ne=fscanf(fid,'%d',1);
x(ne)=0;
y(ne)=0;
E(ne)=0;
A(ne)=0;
for i=1:ne
x(i)=fscanf(fid,'%f',1);
y(i)=fscanf(fid,'%f',1);
E(i)=fscanf(fid,'%f',1);
A(i)=fscanf(fid,'%f',1);
end
x0=fscanf(fid,'%f',1);
y0=fscanf(fid,'%f',1);
p=zeros(2,1);
p(1)=fscanf(fid,'%f',1);
p(2)=fscanf(fid,'%f',1);
fclose(fid);
k=zeros(2,2);
for i=1:ne
dx=x0-x(i);
dy=y0-y(i);
L(i)=sqrt(dx*dx+dy*dy);
C(i)=dx/L(i);
S(i)=dy/L(i);
ke=E(i)*A(i)/L(i);
k(1,1)=k(1,1)+ke*C(i)*C(i);
k(1,2)=k(1,2)+ke*C(i)*S(i);
k(2,1)=k(2,1)+ke*S(i)*C(i);
k(2,2)=k(2,2)+ke*S(i)*S(i);
end
uv=k\p;
dL(ne)=0;
N(ne)=0;
for i=1:ne
dL(i)=uv(1)*C(i)+uv(2)*S(i);
N(i)=E(i)*A(i)/L(i)*dL(i);
end
dL
N