Problem with matrix indexing in for loop
1 view (last 30 days)
Show older comments
HI guys
In this code, I am getting problem when I am trying to find index of object . In for loop if I comment out img=img+obj(x_f,y_f) then Index x_f and y_f shows from 1 to 512 but when I remove comment then indexes changed. I don't know how it is happening in for loop. Can anyone please help to sort out problem. I will appreciate your help
obj=zeros(512);
obj(230:250,230:250)=5;
%theta = pi/2*180;
figure;
subplot(2,2,1);
imshow(obj);
drawnow;
N=512;
x=[-N/2:N/2-1];
y=[-N/2:N/2-1];
theta=pi/180;
img=zeros(512);
for i=1:180
x_f=round( x .* cos(theta*i) + y.* sin(theta * i)+256);
y_f=round( y .* cos(theta*i)- x .* sin(theta * i)+256);
img=img+obj(x_f,y_f);
% subplot(2,2,2);
% imshow(img);
% drawnow;
end
0 Comments
Answers (3)
per isakson
on 29 Jun 2014
Edited: per isakson
on 29 Jun 2014
Here are some links on debugging in Matlab
BTW:
>> x_f(1:5)
ans =
-4 -3 -2 -1 0
Try
>> dbstop if error
0 Comments
Image Analyst
on 29 Jun 2014
x_f and y_f will not change depending on whether the img line is in there or commented out. However the values do go negative and you can't have negative indexes into img. What are you trying to do anyway? Draw sine waves into an image???
5 Comments
See Also
Categories
Find more on Loops and Conditional Statements in Help Center and File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!