Subscript indices must either be real positive integers or logicals

1 次查看（过去 30 天）
RG
RG 2016-8-16
评论： RG 2016-8-17
Hei All,
I have been getting the error message "Subscript indices must either be real positive integers or logicals. " referring to the calculation of z(i, j) whilst working on the code below. I have spent hours trying to fix the issue, but couldn't figure out what I was missing.
a = 0.2302;
N=4;
theta = linspace(0, 2 * pi * pi, N);
r = linspace(a, 2 * a, N);
sigma_TT = r.^4 .* cos(2 .* theta);
x = zeros(N, N);
y = zeros(N, N);
z = zeros(N, N);
for i = 1:N
for j = 1:N
x(i, j) = (cos(theta(i)))' * r(j);
y(i, j) = (sin(theta(i)))' * r(j);
z(i, j) = real(sigma_TT([theta(i), r(j)]));
end
end
The for loop part is actually what I trying to convert from python to MATLAB. In python it is expressed as:
x = r * np.cos(theta[:,None])
y = r * np.sin(theta[:,None])
z = sigma_TT(SHmax, Shmin, Pp, Pm, a, r, theta[:,None])
Any help on this issue would be much appreciated.
  4 个评论
显示 2更早的评论
Ammar Dodin
Ammar Dodin 2016-8-16
编辑：Ammar Dodin 2016-8-16
I am not too familiar with numpy, but I think I understand what the first two lines of your python code are doing. It looks like you're creating new vectors that contain the cosine/sin of each of the values of the vector theta after multiplying them with some constant. I don't understand what z is doing? I am assuming sigma_TT is some function you wrote.
Could you possibly provide the Python code for that function?
RG
RG 2016-8-17
You are right, sigma_TT is a separate function. I managed to fix the issue, apparently I forgot to write sigma_TT function. I will post the solution below just for a reference.

请先登录，再进行评论。

请先登录，再回答此问题。

采纳的回答

RG
RG 2016-8-17
I had to first create a function called sigma_TT:
function sigma_TT = sigma_TT(r, theta)
sigma_TT = r.^4 .* cos(2 * theta);
The code worked well when sigma_TT is called within compute_sTT function:
function compute_sTT
a = 3;
N = 4;
theta = linspace(0, 3 * pi * pi, N);
r = linspace(a, 3 * a, N);
x = zeros(N, N);
y = zeros(N, N);
z = zeros(N, N);
for i = 1:N
for j = 1:N
x(i, j) = (cos(theta(i)))' * r(j);
y(i, j) = (sin(theta(i)))' * r(j);
z(i, j) = sigma_TT(r(j), theta(i));
end
end

更多回答（1 个）

Image Analyst
Image Analyst 2016-8-16
  4 个评论
显示 2更早的评论
Image Analyst
Image Analyst 2016-8-17
I thought my comment would explain it more thoroughly than his original 2-line comment. Anyway, hopefully you looked over the FAQ and maybe found some other good stuff in there.

请先登录，再进行评论。

类别

在 Help Center 和 File Exchange 中查找有关 MATLAB 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by