Why do I get "array indices must be positive integers or logical values" when running this for loop?

i_theta_max =100;
for i_theta = 0:i_theta_max
    theta = i_theta/(i_theta_max)*2*pi;
    xcoord(i_theta)=1*sin(theta);
    ycoord(i_theta)=1*cos(theta);
end

Answer 1

[Sriram Tadavarty]

Hi Spencer,

The access of i_theta in xcoord and ycoord is the issue. In MATLAB, indexing is one based.

Try to update as folllowing:

i_theta_max =100;
for i_theta = 0:i_theta_max
    theta = i_theta/(i_theta_max)*2*pi;
    xcoord(i_theta+1)=1*sin(theta); % Added 1
    ycoord(i_theta+1)=1*cos(theta); % Added 1
end

% or
i_theta_max =100;
for i_theta = 1:i_theta_max+1
    theta = (i_theta-1)/(i_theta_max)*2*pi; % Subtract 1
    xcoord(i_theta)=1*sin(theta);
    ycoord(i_theta)=1*cos(theta);
end

Hope this helps.

Regards,

Sriram

[Spencer Checkoway]

That worked thank you!