Array indices must be positive integers or logical values.

Can't seem to figure out the reason for the error. The array indices, i, as far as I can tell are intergers between 1 and 1000.

Attached is the code:

clear
clc
close all
t = linspace(0,2,1000);
f = zeros(1,length(t));
for i = 1:length(t)
    if  t(1i) <= 1
        f(1i) = 2-(2.*((t(1i)-1).^2));
    elseif t(1i) > 1 
        f(1i) = 0;
    end
end
plot(t,f)

Returns the error:

Array indices must be positive integers or logical values.

Error in aufgabe1 (line 10)

f(1i) = 2-(2.*((t(1i)-1).^2));

Answer 1

[Scott MacKenzie]

You've got a typo in your code. Change the indices

1i

to

i

[Michael Ryan]

Thanks. This worked. For some reason previously MATLAB was telling me to replace i or j with 1i or 1j.

Answer 2

[Walter Roberson]

t = linspace(0,2,1000);

t is a (real) vector of length 1000

    if  t(1i) <= 1

That asks to index the vector t at location 1i . However, 1i means sqrt(-1) which is not real-valued and is not a positive integer.

[Walter Roberson]

t = linspace(0,2,1000);
nt = length(t);
f = zeros(1,nt);
for K = 1:nt
    if  t(K) <= 1
        f(K) = 2-(2.*((t(K)-1).^2));
    elseif t(K) > 1 
        f(K) = 0;
    end
end
plot(t,f)
ylim([-1 3])