MATLAB: Plot inside a function

Question

Hi,

I want to plot Distance (x) vs. Velocity (y).

With my code

function y = fp(x);
d = 75;
a = 1 / 3;
    for i = 1: length(x);
        if x(i) <= 0;
            y(i) = 0;
        elseif x(i) > 0 & x(i) <= d;
            y(i) = a .* x(i);
        elseif x(i) > d;
            y(i) = a .* d;
        end       
end

I execute for example

x = [0:1:100];
plot(x,fp(x))     

and it works. But what I want is to just execute fp(x) and get the plot from the function,

but I get the error "Vectors must of same length" with the code

function y = fp(x);
d = 75;
a = 1 / 3;
    for i = 1: length(x);
        if x(i) <= 0;
            y(i) = 0;
        elseif x(i) > 0 & x(i) <= d;
            y(i) = a .* x(i);
        elseif x(i) > d;
            y(i) = a .* d;
        end
plot(x,y)
end
    

Whats the deal? Thanks!

Answer 1

In the code it looks like you have the plot within your for loop. You need an additional end before the plot line. Does that fix your issue?

function y = fp(x);
d = 75;
a = 1 / 3;
    for i = 1: length(x);
        if x(i) <= 0;
            y(i) = 0;
        elseif x(i) > 0 & x(i) <= d;
            y(i) = a .* x(i);
        elseif x(i) > d;
            y(i) = a .* d;
        end
    end
plot(x,y)
end