Why are my plots empty?
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clear;clc;
%Known Values
r2=140; %input
r3=70.1; %known
r4=70.1; %known
rBE=47.1; %known
r5=140; %unknown
rBC=47.1; %known
theta2=0; %known
theta3=60; %unknown
theta4=60; %unknown
os4=10; %offset from theta4
thetaBE=theta4+os4;%known
theta5=0; %unknown
os3=10; %offset from theta3
thetaBC=theta3+os3; %known
e = zeros(4,360);
%Position
while r2 <= 360
error = 1;
x = [theta3;theta4;theta5;r5]; %Matrix of Initial Guesses
tol = 1e-8;
i = 0;
while ((error > tol) && (i < 1000))
f = fun(x,r2);
j = jac(x);
deltax = j\f;
xnew = x - deltax;
error = abs ((xnew - x)) ./ xnew;
error = max(error);
x = xnew;
i = i + 1;
end
figure(1)
p=plot(r2,x(1),'r.');
xlabel('r2')
ylabel('1')
hold on
figure(2)
p=plot(r2,x(2),'b.');
hold on
figure(3)
p=plot(r2,x(3),'g.');
hold on
figure(4)
p=plot(r2,x(4),'c.');
hold on
e(:,r2) = x;
end
function [F] = fun(x,r2)
r3=70.1; %known
r4=70.1; %known
rBE=47.1; %known
rBC=47.1; %known
theta2=0; %known
thetaBE=70; %known
thetaBC=70; %known
F= [r2*cosd(theta2)+r3*cosd(x(1))-r4*cosd(x(2)); % for x: R2 + R3 - R4
r2*sind(theta2)+r3*sind(x(1))-r4*sind(x(2)); % for y: R2 + R3 - R4
rBE*cosd(thetaBE)-x(4)*cosd(x(3))-rBC*cosd(thetaBC); % for x: RBE - R5 - RBC
rBE*sind(thetaBE)-x(4)*sind(x(3))-rBC*sind(thetaBC); % for y: RBE - R5 - RBC
];
end
function [J] = jac(x)
r3=70.1;
r4=70.1;
os3=10;
os4=10;
rBC=47.1;
rBE=47.1;
J=zeros(4,4);
J(1,1)=r3*cosd(x(1));
J(2,1)=-r3*sind(x(1));
J(3,1)=-rBC*cosd(x(1)+os3);
J(4,1)=rBC*sind(x(1)+os3);
J(1,2)=-r4*cosd(x(2));
J(2,2)=r4*sind(x(2));
J(3,2)=rBE*cosd(x(2)+os4);
J(4,2)=-rBE*sind(x(2)+os4);
J(1,3)=0;
J(2,3)=0;
J(3,3)=-x(4)*cosd(x(3));
J(4,3)=x(4)*sind(x(3));
J(1,4)=0;
J(2,4)=0;
J(3,4)=-cosd(x(3));
J(4,4)=sind(x(3));
end
3 个评论
Arif Hoq
2022-2-25
I think the problem is in your function fun and jac. whenever your dividing in (deltax(k)=jacfunc(k) / ffunc(k)) the its return an inf. I have found 2 output. but still it needs more development.
%Known Values
r2=140; %input
r3=70.1; %known
r4=70.1; %known
rBE=47.1; %known
r5=140; %unknown
rBC=47.1; %known
theta2=0; %known
theta3=60; %unknown
theta4=60; %unknown
os4=10; %offset from theta4
thetaBE=theta4+os4;%known
theta5=0; %unknown
os3=10; %offset from theta3
thetaBC=theta3+os3; %known
e = zeros(4,360);
error = 1;
x = [theta3;theta4;theta5;r5]; %Matrix of Initial Guesses
tol = 1e-8;
ffunc = fun(x,r2);
jacfunc = jac(x);
deltax = (1:length(x))';
%Position
for r2 = 1:360
i = 0;
while ((error > tol) && (i < 1000))
for k = 1:length(x)
deltax(k)=jacfunc(k) / ffunc(k);
end
xnew = x-deltax;
error = abs((xnew-x)./xnew);
error=max(error);
x=xnew;
i=i+1;
end
e1(:,r2) = x;
end
figure(1)
plot(e1(1,:),'o');
('\r_2 [^{o}]');
hold on
plot(e1(2,:),'*');
('\r_2 [^{o}]');
hold on
plot(e1(3,:),'--');
('\r_2 [^{o}]');
hold on
plot(e1(4,:),'o');
('\r_2 [^{o}]');
hold on
xlabel('r2')
ylabel('outputs')
legend('theta3','theta4','theta5','r5')
回答(1 个)
ag
2024-1-4
Hi Caitlynn,
I understand that you are trying to plot the obtained results, and are getting an empty plot.
Arif's suspicion seems to be correct; the issue stems from the calculated values of "jac(x)", which are detailed below.
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/1582321/image.png)
As you can observe, the cancellation occurring in the first two columns leads to a determinant of zero. Consequently, when applying the formula "deltax(i) = det(jj) / det(j)", you end up with "NaN" since it involves division by zero. Such "NaN" values cannot be plotted.
Note - Jacobian with a zero determinant indicates that there is no net change at that specific point in terms of rate.
Hope this helps!
Best Regards,
Aryan Gupta
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