Question

如何用matlab求解方程组：

用MATLAB求解方程组：f1*sin(a1)+9800=l*pi*1025*9.8
f2*sin(a2)+9800=f1*sin(a1)+pi*0.025^2*1025*9.8
,f3*sin(a3)+98=f2*sin(a2)+pi*0.025^2*1025*9.8
sin(a1)+sin(a2)+l=3
f1*cos(a1)=360
f2*cos(a2)=360
f3*cos(a3)=360
七个方程，七个未知量，望大师指教

Answer 1

各个求解的值如下（顺序按f1 f2 f3 a1 a2 a3 l 来排列）：

21778.7871329802
12000.9356630316
-11922.6944325793
-86.4103285726901
-55.0078735996165
-76.9992191199574
1.00058665833736

我的程序：

clc;clear
FFF=@(x) [x(1)*sin(x(4))+9800-x(7)*pi*1025*9.8;
x(2)*sin(x(5))+9800-(x(1)*sin(x(4))+pi*0.025^2*1025*9.8);
x(3)*sin(x(6))+98-(x(2)*sin(x(5))+pi*0.025^2*1025*9.8);
sin(x(4))+sin(x(5))+x(7)-3;
x(1)*cos(x(4))-360;
x(2)*cos(x(5))-360;
x(3)*cos(x(6))-360];
flag=0;
imax=100;i=0;
while(flag~=1)
    [x,fval,flag]=fsolve(FFF,100*(rand(7,1)-1));
    i=i+1;
    if(i>=imax)
        clc;fprintf('不能求解！！\n')
        break;
    end
end

想能够帮到你