Issue in plotting of output after function

Unable to plot output after function.

I gave my script below

syms theta
A = cos(theta).*[1 5 6; 2 9 3; 5 1 0];
B = tan(2*theta).*[8 5 1; 0 1 6; 2 4 7];
myfun = @(t,y)scriptname(t,y,A,B);
% dummy values for tspan and y0
tspan = [0 1];
y0 = [0; 0; 0];
% ode solver
sol = ode45(myfun,tspan,y0);
function dydt = scriptname(t,y,A,B)
V = [1; 5; 3];
% evaluation of A and B (numerical) with theta = y(3)
An = double(subs(A,y(3)));
Bn = double(subs(B,y(3)));
dydt = V-((An+Bn)*y);
end
for i=1.:3.
 stator=y(:,i);
 figure(1.);
 subplot(2.,2.,i);
 plot(t,stator);
 xlabel('time');
 ylabel('Current');
 title(['stat current # ',int2str(i)]);
 end

iam getting error like this

  Function definitions in a script must appear at the end of the file.
Move all statements after the "scriptname" function definition to before the first local function definition.

How to resolve this??

Thanks in advance

Answer 1

[KSSV]

function myfun()
syms theta
A = cos(theta).*[1 5 6; 2 9 3; 5 1 0];
B = tan(2*theta).*[8 5 1; 0 1 6; 2 4 7];
myfun = @(t,y)scriptname(t,y,A,B);
% dummy values for tspan and y0
tspan = [0 1];
y0 = [0; 0; 0];
% ode solver
sol = ode45(myfun,tspan,y0);
%% Plot here 
plot(sol.x,sol.y)
function dydt = scriptname(t,y,A,B)
V = [1; 5; 3];
% evaluation of A and B (numerical) with theta = y(3)
An = double(subs(A,y(3)));
Bn = double(subs(B,y(3)));
dydt = V-((An+Bn)*y);

Save the aboove code in myfun.m and run it.

[Bathala Teja]

and then how to plot??

[KSSV]

Check Sol, it will be a structure with required values. See it's fields and plot what you want.

[Bathala Teja]

Iam new to matlab.

i didnt get what your are suggesting.

I want the output waveforms after compiling script.

Can you explian clearly.

[KSSV]

I have shown it in code already....check it.

[Bathala Teja]

After compiling your code(which you gave), it is giving this error

Unable to resolve the name Sol.x.

Error in Untitled5 (line 151)
plot(Sol.x,sol.y)

[KSSV]

The variable is sol not sol (No capitlal S). Typo error. Edited the code.

[Bathala Teja]

Is there any way to plot without making entire script as function(means without using function myfun() at starting)???

[KSSV]

syms theta
A = cos(theta).*[1 5 6; 2 9 3; 5 1 0];
B = tan(2*theta).*[8 5 1; 0 1 6; 2 4 7];
myfun = @(t,y)scriptname(t,y,A,B);
% dummy values for tspan and y0
tspan = [0 1];
y0 = [0; 0; 0];
% ode solver
sol = ode45(myfun,tspan,y0);
%% Plot here 
plot(sol.x,sol.y)

Write the above in a min file. Save the below into a function.

function dydt = scriptname(t,y,A,B)
V = [1; 5; 3];
% evaluation of A and B (numerical) with theta = y(3)
An = double(subs(A,y(3)));
Bn = double(subs(B,y(3)));
dydt = V-((An+Bn)*y);

Now run the main file.

[Bathala Teja]

sorry to bothering you again, one last doubt.

i followed your 1st method(keeping whole script as function), i am getting all waveforms in one graph. How to plot each solution separatley.

[KSSV]

figure
plot(sol.x,sol.y(1,:))
figure
plot(sol.x,sol.y(2,:))
figure
plot(sol.x,sol.y(3,:))