Help me with this task using (Euler`s method)

Question:

Use this method to solve the following IVP:

A series RC circuit with R = 5 W and C = 0.02 F is connected with a battery of E = 100 V. At t = 0, the voltage across the capacitor is zero.

(a) Obtain the subsequent voltage across the capacitor.

(b)find the true error if the exact solution is: Vc = V(1 – e^(-t/RC))

Hint:

Use the formula

r(dq/dt)+(q/c)=v

---------------------------------------------

It is giving me msg operator '*' is not supported for operands of type 'function_handle'

also i wanna ypu give me advices on my work if i working right or wrong to improve as it`s my first time to use matlab

My Work:

R=5;
C=0.02;
E=100;
Y0=0;
Xinitial=0;
Xfinal=1; 
h=0.01;
X=Xinitial:h:Xfinal;
Y = zeros(size(X));
N=(Xfinal-Xinitial)/h;
for i=1:N-1
Ydot=@(t,q) (E-q/C)/R;
Y(i+1) = Y(i) + h*(Ydot);
end
Vreuler= Y0 / C;
Exact=E * (1 - exp(-X/(R*C)));
Error=(Exact-Vreuler)/Exact;
polt(x.y); grid onh

Answer 1

[James Tursa]

The function handle is something you only need to create once, before the for-loop starts. Then call that function handle with your state inside the loop. E.g.,

Ydot = @(t,q) (E-q/C)/R;
Y(1) = Y0;
for i=1:N-1
    Y(i+1) = Y(i) + h*Ydot(X(i),Y(i));
end

Then the plot would be

plot(X,Y,X,Exact); grid on

And this is a more robust way of defining N:

N = numel(X);

[Kamal Mohamed]

Now it give me msg Undefined function or variable 'x'

and error in line 9

Y= zeros(size(x));

R=5;
C=0.02;
E=100;
Y0=0;
Xintial=0;
Xfinal=0;
h=0.01;
X=Xintial:h:Xfinal;
Y= zeros(size(x));
N=numel(X);
Ydot = @(t,q) (E-q/C)/R;
Y(1)= Y0 ;
for i= 1:N-1
    Y(i+1) = Y(i) + h*Ydot(X(i),Y(i));
end
Vreuler = y0 /C ;
Exact = E * (1-exp(-X/(R*C)));
Error = (Exact - Vreuler) / Exact;
polt(X.Y,X,Exact); grid on

[James Tursa]

MATLAB is case sensitive. You had used uppercase X in your first post and you need to stay with that. E.g.,

Y = zeros(size(X)); % UPPERCASE X, not lowercase x

Also your plot needs to change that period to a comma and spell plot properly

plot(X,Y,X,Exact); grid on

[Kamal Mohamed]

Okay Thanks so much :D