视频

拓展学习

1．平面桁架结构受力分析问题

alpha=sqrt(2)/2;

A=[0,1,0,0,0,-1,0,0,0,0,0,0,0;

   0,0,1,0,0,0,0,0,0,0,0,0,0;

   alpha,0,0,-1,-alpha,0,0,0,0,0,0,0,0;

   alpha,0,1,0,alpha,0,0,0,0,0,0,0,0;

   0,0,0,1,0,0,0,-1,0,0,0,0,0;

   0,0,0,0,0,0,1,0,0,0,0,0,0;

   0,0,0,0,alpha,1,0,0,-alpha,-1,0,0,0;

   0,0,0,0,alpha,0,1,0,alpha,0,0,0,0;

   0,0,0,0,0,0,0,0,0,1,0,0,-1;

   0,0,0,0,0,0,0,0,0,0,1,0,0;

   0,0,0,0,0,0,0,1,alpha,0,0,-alpha,0;

   0,0,0,0,0,0,0,0,alpha,0,1,alpha,0;

   0,0,0,0,0,0,0,0,0,0,0,alpha,1];

b=[0;10;0;0;0;0;0;15;0;20;0;0;0];

f=A\b;

disp(f')

2．小行星运行轨道计算问题

xi=[1.02,0.87,0.67,0.44,0.16];

yi=[0.39,0.27,0.18,0.13,0.13];

A=zeros(length(xi));

for i=1:length(xi)

    A(i,:)=[xi(i)*xi(i),2*xi(i)*yi(i),yi(i)*yi(i),2*xi(i),2*yi(i)];

end

b=-ones(length(xi),1);

ai=A\b

或者：

xi=[1.02,0.87,0.67,0.44,0.16]';

yi=[0.39,0.27,0.18,0.13,0.13]';

A=[xi.*xi,2*xi.*yi,yi.*yi,2*xi,2*yi];

b=-ones(length(xi),1);

ai=A\b

 

>> f=@(x,y) 2.4645*x.^2-0.8846*x.*y+6.4917*y.^2-1.3638*x-7.2016*y+1;

>> h=ezplot(f,[-0.5,1.2,0,1.2]);