## Matlab

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first time user syntax help Posted by goaddr on 10 May 2011 at 9:32 AM
Hey, I have a 2048x2048 matrix with values of either 0 or 1 which is called "white". I need to find the total number of 3x3 blocks in the matrix where each data point has a value of 1, ie,

1 1 1
1 1 1
1 1 1

Im a first time user and I think that my problem is syntax. My code is as follows,

x=0

for i=2:2047 j=2:2047

if white(i-1,j-1)==1 & white(i-1,j)==1 & white(i-1,j+1)==1 & white(i,j-1)==1 & white(i,j)==1 & white(i,j+1)==1 & white(i+1,j-1)==1 & white(i+1,j)==1 & white(i+1,j+1)==1

x=x+1

end

y=sum(x)

end

Ive been at it for a few hours and any help would be really appreciated. Ill be spending the rest of the afternoon trying to solve this problem....

Thanks for your help!

Re: first time user syntax help Posted by sambo8 on 10 May 2011 at 11:47 PM
Well I don't know how the matrix white is generated but I have a code for you. I took the example of a 6x6 matrix with two blocks and it works fine. Here's the code, but in your case, you should replace 3(6-3) by 2045(2048-3) in the for loops.

```white = [1 1 1 0 0 0; 1 1 1 0 0 0; 1 1 1 0 0 0; 0 0 0 1 1 1; 0 0 0 1 1 1; 0 0 0 1 1 1];

%      1     1     1     0     0     0
%      1     1     1     0     0     0
%      1     1     1     0     0     0
%      0     0     0     1     1     1
%      0     0     0     1     1     1
%      0     0     0     1     1     1

block=0;
for i=0:3

for j=0:3

b=1;
count=0;

while(b<=3)
c=1;
while(c<=3)
if white(i+b,j+c)==1,
count = count+1; % check if there are nine consecutive ones in three colums and lines and sets count to nine
end

if (count==9),
block = block+1;  % if there are nine consecutive ones, count one block
end

c=c+1;
end

b=b+1;
end

clear count;
end
end

fprintf('The total number of blocks is: %d\n',block) %display in the command window the result  ```

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