Index in position 1 is invalid. Array indices must be positive integers or logical values Error

Pdata=0:floor(length(pressure01)/400);
for i=0:length(pressure01)
    for j=0:floor(length(pressure01)/400)
        if mod(i,400)==0;
            Pdata(j)=pressure01(i,1);
        end
    end
end

Im trying to get the code to work but it gives me an error in line 5 saying

Index in position 1 is invalid. Array indices must be

positive integers or logical values.

pressure01 is a column vector, not sure whats wrong

[Voss]

Indexing in MATLAB starts at 1, not at 0.

https://www.mathworks.com/company/technical-articles/matrix-indexing-in-matlab.html#:~:text=Remember%3A%20MATLAB%20uses%201%2Dbased,to%20see%20in%20mathematical%20textbooks.

Answer 1

[Torsten]

Array indexing in MATLAB starts with 1, not with 0. But you try to set

Pdata(0)=pressure01(0,1);

in your nested loop for i = 0 and j = 0 (so just at the start).