How can I show a graph from the function?

Nc=100; 
c = linspace(10,60,Nc)
function [t,th,pass] = lab1(c0,k0) 
  
J=20; 
opt=[]; 
F0=0; 
omega=0; 
  
dt=0.01;            % sampling time interval 
npt=2000;           % number of sampling points 
tspan=(1:npt)*dt;   % time instants where x(t) is simulated 
idx=0; 
pass=[]; 
  
th_lim1=65/180*pi;  % [rad]  
th_lim2=3/180*pi;   % [rad] 
b_max=3.5;          % [rad/s] 
 
k=k0; 
for i=1:length(c0)
    for j=1:length(k0)
        ctmp=0;
        ktmp=0;
        c=c0(i);
        k=k0(j);
        th0=[0;b_max];
        [t,th]=ode45(@sdof,tspan,th0,opt,J,c,k,F0,omega);
    end

end 
end 

function G=sdof(t,x,J,c,k,F0, omega)

the code above are function .

G=[x(2);(-c*x(2)-k*x(1)+F0*cos(omega*t)//J];
end 

Invalid use of operator.

Error in connector.internal.fevalMatlab

Error in connector.internal.fevalJSON

This code below is the plotting for the function .

 
plot(t,th(:,1)*180/pi)
    title('Displacement vs Time of a Swinging Door')
    xlabel('Time(Seconds)')
    ylabel('Displacement(Degrees)')
    
    plot([0,20],[1,2]*(65));

Attempt to execute SCRIPT lab1 as a function:

C:\Users\joe_p\Desktop\mec721\lab1.m

Error in lab1 (line 1)

[t,th,pass]=lab1(10,30)

That is error .

Please someone explain why i keep getting this error and explain how i can get the graph to work.

Answer 1

[VBBV]

G=[x(2);(-c*x(2)-k*x(1)+F0*cos(omega*t)/J];  % seems you have used  // erroneously 
end 

it is a division operator unlike a comment in C++ language

[VBBV]

Call the function from command window instead of running from script

>>lab1(10:60,30:60)

[Perry fung]

Attempt to execute SCRIPT lab1 as a function:

C:\Users\joe_p\Desktop\mec721\lab1.m

[Perry fung]

that error pop out

[VBBV]

Nc=10; 
c0 = linspace(10,60,Nc);
k0 = linspace(0,20,Nc/2);
[t,th,pass] = lab1(c0,k0)

t = 2000×1

0.0100 0.0200 0.0300 0.0400 0.0500 0.0600 0.0700 0.0800 0.0900 0.1000

th = 2000×2

0 1.0000 0.0075 0.5481 0.0116 0.2993 0.0139 0.1624 0.0151 0.0869 0.0157 0.0454 0.0160 0.0225 0.0162 0.0099 0.0163 0.0030 0.0163 -0.0008

pass =

     []

        plot(t,th(:,1)*180/pi)
        title('Displacement vs Time of a Swinging Door')
        xlabel('Time(Seconds)')
        ylabel('Displacement(Degrees)')

         

 
function [t,th,pass] = lab1(c0,k0) 
  
J=20; 
opt=[10; 20]; 
F0=0; 
omega=0; 
  
dt=0.01;            % sampling time interval 
npt=2000;           % number of sampling points 
tspan=(1:npt)*dt;   % time instants where x(t) is simulated 
idx=0; 
pass=[]; 
  
th_lim1=65/180*pi;  % [rad]  
th_lim2=3/180*pi;   % [rad] 
b_max=3.5;          % [rad/s] 
 
k=k0; 
for i=1:length(c0)
    for j=1:length(k0)
        ctmp=0;
        ktmp=0;
        c=c0(i);
        k=k0(j);
        th0=[0;b_max];
        [t,th]=ode45(@(th0,opt) sdof(th0,opt,J,c,k,F0,omega),tspan,[0 1]);      
     
    end
   
end 
       
function G=sdof(t,x,J,c,k,F0, omega)
G=[x(2);-c*x(2)-k*x(1)+F0*cos(omega*t)/J];
end 

end

 
    

Answer 2

[Image Analyst]

Attach your whole m-file.

You can't have a script followed by functions unless the functions end with "end", which yours don't. Your for loops end with end but the functions don't. Here is your script:

Nc=100; 
c = linspace(10,60,Nc)

Notice that the script never even calls any of the functions defined below it in the file.

The m-file should look like

Nc=100; 
c0 = linspace(10,60,Nc)
k0 = 1; % Whatever...
% Now call the main function:
[t,th,pass] = lab1(c0,k0) 

% Now define all your functions AFTER your script 
% and finish each one with an "end" statement.
%=====================================================================================
function [t,th,pass] = lab1(c0,k0) 
% Its code...
end % Need final closing end statement

%=====================================================================================
function G=sdof(t,x,J,c,k,F0, omega)
% Its code...
end % Need final closing end statement