Plot function with varying variable

Hello,

I am fairly new to Matlab and having an issue with a script I'm writing. The goal is to plot a few variations of function f on the same graph. The plot will have f on the y axis and z on the x axis. Function f is a function of z and y, and function f itself depends on the value of z. I want to plot for z=1 through 5. Below is what I have so far and I'm having trouble figuring out the problem. Thanks in advance for any help! (My actual functions are a bit more complicated than the example below, but with the solution to this example I should be able to apply)

for z=1:1:5
    y=2
    if z<=1
        f=z*y
    elseif z>1
        f=2*z*y
    end
    plot(z,f)
    hold on
end

Answer 1

[Stephen23]

The MATLAB approach is to use logical indexing, e.g.:

z = 0:0.1:5;
y = 2;
f = z*y;
idx = z>1; % logical index
f(idx) = 2*z(idx)*y;
plot(z,f,'-x')