how to create a piecewise function using nested for/if-else loops

I have no idea how to use MATLAB:

I'm trying to generate a two pulse waveform like so:

x = 0:.02:2;
g = zeros(length(x));
for k = 0:length(x)
    if 0<= x(k) < 1/3
        g(k) = 0;
    elseif 1/3 <= x(k) < 1/2
        g(k) = 1;
    elseif 1/2 <= x(k) < 4/3
        g(k) = 0;
    elseif 4/3 <= x(k) <5/3
        g(k) = -1;
    else 
        g(k) = 0;
   end
end
plot(x,g, 'r')

but every time I try and run the program it gives me an error code saying "Subscript indices must either be real positive integers or logicals."

I don't know wht to do

Answer 1

[Walter Roberson]

    if 0<= x(k) < 1/3

in MATLAB means the same as

      if all((0<= x(k)) < 1/3)

the 0<=x(k) part returns either false (0) or true (1) . The < 1/3 part then compares that 0 or 1 to 1/3 .

There are no MATLAB operators to compare ranges (I am not sure I have ever see a language that has such an operation, but perhaps there is.)

You need to code each part separately:

if 0 <= x(k) && x(k) < 1/3