Help with knowing what kind of vector im using

could someone tell me what th2s=[th2s,y(2)] means?

th1=1;
th2=1;
w1=0;
w2=0;
hs(1)=[0.05];
hs(2)=[0.05/2];
hs(3)=[0.05/4];
hs(4)=[0.05/8];
hs(5)=[1/1000];
th2s=[];

for h=hs %for all the stepsizes
    y=[th1,th2,w1,w2]; we have this vetir which has the values
    N=100/h;
    for i=1:N
        k1= h*fpend(y);
        k2=h*fpend(y + k1/2);
        k3=h*fpend(y + k2/2);
        k4= h*fpend(y + k3);
        y = y + (k1 + 2*k2 + 2*k3 + k4) / 6;
    end
    th2s=[th2s,y(2)]
end

Answer 1

[Cris LaPierre]

It is appending y(2) to the end of the vector th2s at the end of each h loop.

th2s=[];

for a=1:3
    a
    th2s = [th2s,a]
end

a = 1

th2s = 1

a = 2

th2s = 1×2

1 2

a = 3

th2s = 1×3

1 2 3

[Lavorizia Vaughn]

Is there a better way of doing this?

[Cris LaPierre]

It looks like you are doing a 4th order runge-kutta. There are a lot of questions about implementing that on Answers. Take a look at some of them for ideas. Your code looks pretty clean. Just be sure to place a % before any comments.

[Lavorizia Vaughn]

i am doing a rk4. and i wish to find a better way. this way seems a bit hard.