Plot not showing any data

Hey, I am new to MATLAB. I am running the following code and cant figure out why the plot shows no data. I know it is showing only the last iteration, but I dont know how to fix it. I have tried using/not using a for loop, I basically need a plot of v vs t. But I would like to learn how to plot results of a for loop. PLEASE HELP:

    %for 
        t= [-5.0:0.5:50.0] %s
        if t>=0 & t<=10
            v=(11*(t.^2))-(5*t)
        elseif t>=10 & t<=20
            v=1100-(5*t)
        elseif t>=20 & t<=30
            v=(50*t)+2*((t-20)^2)
        elseif t>30
            v=1520* exp(-0.2*(t-30))
        else 
            v=0
        end
        format long g
        
          
    %end
    %Tab=table(t(:), v(:))
   
plot(t(:),v(:))
hold on

File is also attached.

Answer 1

[Adam Danz]

The solution involves matlab indexing which is a very basic skill to know before making much progress.

This should get you started.

t= [-5.0:0.5:50.0];
v = zeros(size(t)); 

idx = t>=0 & t<=10; 
v(idx) = (11*(t(idx).^2))-(5*t(idx)); 

idx = t>=10 & t<=20; 
v(idx) = 1100-(5*t(idx));

% repeat for the other indices

[Shantanu Chatterji]

Thanks Mr. Danz!

Does this mean that a for loop/if statement is not required or would this work even if i added for/if statements to this?

Thanks, you are awesome!

[Adam Danz]

This solution does not need any loops or conditional statements.

Indexing acts as conditons. The "idx" variable is a logical vector identifying which values to access and change.