The solve function doesn't work properly

15 次查看（过去 30 天）
Imanol Fernandez de arroyabe Zabala
回答： Torsten 2023-1-20
Hello everyone. I'm trying to solve an equation system. This particular system has variables that are functions of time, and when I try to use a loop to analyze them they don't acquire the correct values. However, if I do the same changing the time values manually it does work. Any idea why this is? Thanks in advance.
syms l1 l2 l3 H B phi gamma theta omega1 omega2 omega3 t beta
l1 = 0.124;
l2 = 0.27;
l3 = 0.095;
B = 0.238;
H = 0.117;
array_valores1 = zeros(1,30);
array_valores2 = zeros(1,30);
array_valores3 = zeros(1,30);
i = 0
t = 21
% while t < 31
gamma = pi -pi*t/40;
array_gamma(i+1) = pi -pi*t/40;
eq1 = l3*cos(gamma) - l2*cos(phi) + l1*sin(theta) + B == 0;
eq2 = l3*sin(gamma) - l2*sin(phi) -l1*cos(theta) + H == 0;
sol1 = solve([eq1 eq2], [theta phi]);
phi = vpa(sol1.phi(1))
theta = vpa(sol1.theta(1))
% i = i+1;
% end

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回答（1 个）

Torsten
Torsten 2023-1-20
Ran in:
syms l1 l2 l3 H B phi gamma theta
eq1 = l3*cos(gamma) - l2*cos(phi) + l1*sin(theta) + B == 0;
eq2 = l3*sin(gamma) - l2*sin(phi) -l1*cos(theta) + H == 0;
sol = solve([eq1 eq2], [theta phi]);
Warning: Solutions are only valid under certain conditions. To include parameters and conditions in the solution, specify the 'ReturnConditions' value as 'true'.
t = 21:31;
theta_array = zeros(2,numel(t));
phi_array = zeros(2,numel(t));
for i = 1:numel(t)
theta_array(:,i) = double(subs(sol.theta,[l1 l2 l3 H B gamma],[0.124,0.27,0.095,0.117,0.238,pi*(1-t(i)/40)]));
phi_array(:,i) = double(subs(sol.phi,[l1 l2 l3 H B gamma],[0.124,0.27,0.095,0.117,0.238,pi*(1-t(i)/40)]));
end
figure(1)
plot(t,theta_array)
grid on
figure(2)
plot(t,phi_array)
grid on

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