How can I put the values that I made in a for and if loop into a vector?

This is what I've got so far, there might be other issues too.

for i = 0:L;
if i == 0:L_1    
v_1(i) = P-(P*L_1)/L
    m_1(i) = (P-((P*L_1)/L))*i
    elseif i == L_1:L
    v_1(i) = ((P*L_1)/L)-P
    m_1(i) = (P-((P*L_1)/L))*i - P*(i-L_1)
    end
   v = (i,v_1(i))
   m = (i,m_1(i))
end

[Dennis]

I think your if synthax might be wrong. Can you try

for i = 1:L  
if i>=0 && i<L_1
       v_1(i) = P-(P*L_1)/L;
       m_1(i) = (P-((P*L_1)/L))*i;
else
       v_1(i) = ((P*L_1)/L)-P;
       m_1(i) = (P-((P*L_1)/L))*i - P*(i-L_1);
end
end

What do you want to happen when i==L_1 ? v_1 and m_1 are vectors and do you need the i=0 case?

[Shounak Shastri]

Dennis' code is correct. There is a mistake in your if statement

Also, the way you are trying to store the values of v and m is wrong. If you execute Dennis's code, you will have the values of v and m in v_1 and m_1. No need of separate variables.

[Sophie]

The code you provided ran with no errors. When i=0, v has two values: one that comes from the function provided in 0<i<L_1 and the other value from the function in L_1<i<L. And I'm trying to graph the data, so the i=0 case would be helpful to have

[Dennis]

for i = 0:L  
if i>=0 && i<L_1
       v_1(i+1) = P-(P*L_1)/L;
       m_1(i+1) = (P-((P*L_1)/L))*i;
else
       v_1(i+1) = ((P*L_1)/L)-P;
       m_1(i+1) = (P-((P*L_1)/L))*i - P*(i-L_1);
end
end

this inculdes i=0, right now at i==L_1 only the else part is executed, do you want 2 values at the same i?

[Sophie]

Thank you. And yes, if that's possible. The graph needs to have a vertical line at i = L_1 between the two values

[Dennis]

the problem here is that we are using i to index our vectors, so our 2nd calculation would overwrite our first value. Is i important for plotting or can we add another value to our vectors at the end?

[Sophie]

It's important for plotting; that's why I started off with the two different parts (0<=i<=L_1 and L_1<=i<=L) with different variable names (v_1 and v_2, m_1 and m_2), but I couldn't put them in the same vector to graph

[Sergey Kasyanov]

Sophie, try this:

plot([v1,v2],[m1,m2])

[Sophie]

That fixed it, thank you!

Answer 1

[Sergey Kasyanov]

Code improvements:

%Range of i for different calculation formulas
FirstRange=[1:L_1];
SecondRange=[L_1:L];
%Create array with result of calculations
v=[ones(length(FirstRange),1)*(P-(P*L_1)/L)
    ones(length(SecondRange),1)*(((P*L_1)/L)-P)];
m=[FirstRange'*(P-((P*L_1)/L))
    (P-((P*L_1)/L))*SecondRange' - P*(SecondRange'-L_1)];

Notes:

1) FirstRange - row array, FirstRange' - column array with same data.

2) ones(length(FirstRange),1) - column array with ones with the same length as FirstRange.

3) In (P-((P*L_1)/L))*i - P*(i-L_1) the i is replaced by array with i values - SecondRange. That also works.

Yoy may plot graph with that:

plot(m,v)

If you want to plot a rectangle you may use function rectangle.

[Sophie]

This syntax didn't work when I tried using it.

[Sergey Kasyanov]

Strange. I have tested it. Can you adduce error message?