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%%刚体系统受力分析+符号推导  %%%
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clc;              %清除屏幕
clear all;        %清除内存

syms P q a A B X  %定义参数
B=[0;0;0;0;0;P+q*a;P*a+3*q*a*a/2;0;q*a;-3*q*a*a/2]; %B矩阵

%----下面是A矩阵中非0元素
A(1,1)=-sqrt(2)/2;A(1,3)=1;A(2,1)=sqrt(2)/2;A(2,2)=1;
A(3,3)=-1;A(3,5)=sqrt(2)/2;A(4,4)=1;A(4,5)=sqrt(2)/2;
A(5,1)=sqrt(2)/2;A(5,6)=1;A(5,9)=1;
A(6,1)=-sqrt(2)/2;A(6,2)=-1;A(6,7)=1;A(6,10)=1;
A(7,2)=-a;A(7,10)=2*a;A(8,5)=-sqrt(2)/2;A(8,9)=-1;
A(9,4)=-1;A(9,5)=-sqrt(2)/2;A(9,8)=1;A(9,10)=-1;
A(10,4)=a;A(10,10)=2*a;

X=simplify(inv(A)*B); %求解

disp(['S1=',char(X(1))])%在屏幕上显示结果
disp(['S2=',char(X(2))])%在屏幕上显示结果
disp(['S3=',char(X(3))])%在屏幕上显示结果
disp(['S4=',char(X(4))])%在屏幕上显示结果
disp(['S5=',char(X(5))])%在屏幕上显示结果
disp(['XA=',char(X(6))])%在屏幕上显示结果
disp(['YA=',char(X(7))])%在屏幕上显示结果
disp(['YB=',char(X(8))])%在屏幕上显示结果
disp(['XC=',char(X(9))])%在屏幕上显示结果
disp(['YC=',char(X(10))])%在屏幕上显示结果