for,if statements

I need to create a data vector that is 0 to 200 days in 0.1 increments and is 0 at all times except on days 10-30, 1 for days 10-30. I tried this and it didn't work. I think it has something to do with the "if ii = 1:length" part because if I use "if ii = t" it says "Array indices must be positive".

t = [0:0.1:200]; %Days with 0.1 sample spacing
for ii = 1:length(t) 
    if ii == 10.000:30.000
        y1(ii) = 1;
    else y1(ii) = 0;
    end
end

Answer 1

[Walter Roberson]

if ii >= 10 && ii <= 30

[Marcos Perez Rodriguez]

What if I wanted to keep that interval of 0.1? Because It works without that interval but when I do

for ii = 1:0.1:length(t)

it doesn't work.