How can I solve problem regarding subscript indices in for loop?

Hello Matlab users,

I get error massage, when I run the program.

Subscript indices must either be real positive integers or logicals.

Error in Test_2017_02_14 (line 82) clipping(end,:) = clipping(end,:)*1/2;

here is my code:

radius_max = 3200;
angle = 0:(2*pi/6):2*pi;
radius = [0 690 1390 1990 2490 2890];

r_m = [(1/2 * (radius+[0 radius(1:end-1)])) radius_max];
[angle_mat,radius_mat]=meshgrid(angle,radius);
[X,Y] = pol2cart(-(angle_mat)+pi/2,radius_mat);

surface = 1/4*pi*(([radius_mat(2:end,:);ones(1,length(angle))*(2*radius_max-radius(end))]+ radius_mat).^2-([radius_mat(1,:);radius_mat(1:end-1,:)]+radius_mat).^2)
/(length(angle)-1);

angle_fine = 0:(2*pi/60):2*pi;
laf = length(angle_fine);
radius_fine = 0:10:radius_max; 
[angle_fine_mat,radius_fine_mat] = meshgrid(angle_fine,radius_fine);
[X_fine,Y_fine] = pol2cart(-(angle_fine_mat)+pi/2,radius_fine_mat);

surface_fine = 1/4*pi*(([radius_fine_mat(2:end,:);radius_fine_mat(end,:)]+radius_fine_mat).^2-([radius_fine_mat(1,:);radius_fine_mat(1:end-1,:)]+radius_fine_mat).^2) /(laf-1);

angle_ex = [2/9 1/2 5/6 7/6 3/2 16/9]*pi;   
radius_ex = 2075; 
[angle_ex_mat,radius_ex_mat]=meshgrid(angle_ex,radius_ex);
[X_ex,Y_ex] = pol2cart(angle_ex_mat-pi/2,radius_ex_mat);

angle_ufine = 0:(2*pi/600):2*pi;
radius_ufine = 0:2.5:radius_max;
[angle_ufine_mat,radius_ufine_mat]=meshgrid(angle_ufine,radius_ufine);
[X_ufine,Y_ufine] = pol2cart(-(angle_ufine_mat)+pi/2,radius_ufine_mat);
[~,index_a] = intersect(angle_ufine,angle);
[~,index_r] = intersect(radius_ufine,r_m);

angle_e = 0:(2*pi/6):6*pi;
radius_e = [radius radius_max];
[angle_mat_e,radius_mat_e]=meshgrid(angle_e,radius_e);

angle_fine_e = 0:(2*pi/600):6*pi;
radius_fine_e = 0:2.5:radius_max;
[angle_fine_mat_e,radius_fine_mat_e] = meshgrid(angle_fine_e,radius_fine_e);

radius_flow = [0 0.2 0.4 0.6 0.8 0.9 1]*radius_max;

flow_left = [0.058; 0.0603; 0.080; 0.119; 0.138; 0.124; 0]; 
flow_right = [0.058; 0.063; 0.079; 0.099; 0.104; 0.096; 0];  

FL = transpose(spline(radius_flow,flow_left,radius_fine));
FR = transpose(spline(radius_flow,flow_right,radius_fine));  

flow_fine(:,1:(laf-1)/2) = repmat(FL,1,(laf-1)/2)+(repmat(FR,1,(laf-1)/2)-repmat(FL,1,(laf-1)/2)).*(angle_fine_mat(:,1:(laf-1)/2)/pi);

flow_fine(:,(laf+1)/2:laf) = repmat(FR,1,(laf+1)/2)+(repmat(FL,1,(laf+1)/2)-repmat(FR,1,(laf+1)/2)).*((angle_fine_mat(:,(laf+1)/2:laf)-pi)/pi);

flow_fine = circshift(flow_fine(:,1:end-1),round(laf*(-110)/360),2);
flow_fine = [flow_fine flow_fine(:,1)];

index = 1:(laf-1)/6:laf;
flowXsurf = flow_fine.*surface_fine;

for i = 1:6
      r_l = (i>1)*1/2*(radius(i)+radius((i>1)*(i-1)+(i==1)));  
      r_h = (i<6)*1/2*(radius(i)+radius((i<6)*(i+1)+(i==6))) + (i==6)*radius_max;
      clipping = flowXsurf(find(radius_fine==r_l):find(radius_fine==r_h),:); 
      clipping = [clipping(:,end-find(angle_fine==pi/6)+1:end-1)...
      clipping(:,1:end-find(angle_fine==pi/6)+1)];
    if i>1
        clipping(1,:) = clipping(1,:)*1/2;
    end
    if i<6
        clipping(end,:) = clipping(end,:)*1/2;
    end
    clipping(:,index) = clipping(:,index)*1/2;
    for j = 1:6
       flow(i,j) = sum(sum(clipping(:,index(j):index(j+1))))/surface(i,j);  
    end
end
flow = [flow flow(:,1)];

Thank you in advance.

[Kevin Chng]

Subscript indices must either be real positive integers or logicals.

Error in Test_2017_02_14 (line 82)

clipping(end,:) = clipping(end,:)*1/2;

Or your clipping is empty?

[KSSV]

Are you sure with the line number of error? According to me that line has no issues:

clipping(end,:) = clipping(end,:)*1/2;

It has nothing to do with indices.

[Omar Rashell]

cliping is empty

[Kevin Chng]

You can't index to empty variable.

[Stephen23]

"You can't index to empty variable."

With an empty index you can:

>> A = [];
>> A([])
ans = []

[Kevin Chng]

great to know this. A([])

Answer 1

[Omar Rashell]

radius_fine = 0:10:radius_max;

I think, I got it. I tried as bellows: radius_fine = 0:1:radius_max; radius_fine = 0:5:radius_max;

Then it works. I got no errr Massage.

Tank you guys for your afford.