Number of zeros in a matrix

2012 11 17
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I need to create a function where I have a matrix and the function returns the number of zeros in that matrix. I need to do this using the if condition.
Then write in a .txt file which columns had more than 12 zeros.
Can someone help me out with this?
Thank you very much.

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Azzi Abdelmalek
Azzi Abdelmalek 2012-11-17
Why did you need to do it with if condition?
Bob Choy
Bob Choy 2012-11-17
Because thats what I usually work with but if thats impossible nevermind it.

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Matt Fig
Matt Fig 2012-11-17
编辑：Matt Fig 2012-11-17

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The number of zeros in the matrix A is:
sum(~A(:))
So we can make this a function:
f = @(x) sum(~x(:));
Now test it:
x = [1 2 3;0 0 0;3 0 9]
f(x)

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Bob Choy
Bob Choy 2012-11-18
It works, awesome! Now to the hard part, how do I find out which columns have more than 12 zeros and then write that info into a .txt file?
Thank you.
Matt Fig
Matt Fig 2012-11-18
What do you mean by write to a text file? You want to write only those columns that do or do not have more than 12 zeros? You want to write the whole column including all the zeros?
Bob Choy
Bob Choy 2012-11-18
I want to write in a .txt file numbers of the columns that have more than 12 zeros. E.g. say I wanted the columns with atleast one zero. (Ignore the "if true" nonsense]
if true
% code
end
M = 1 0 1 1
1 1 1 0
I want the function to save a .txt file with the numbers 2 and 4.
Matt Fig
Matt Fig 2012-11-18
M = [1 0 1 1;1 1 1 0]
fid = fopen('mytext.txt','wt')
fprintf(fid,'%i ',find(sum(~M) >= 1))
fclose(fid)
Bob Choy
Bob Choy 2012-11-18
Thank you so much! Keep up the good work, cheers!

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