1 == 0 ?

function nbDeZero = EstMatriceCreuse(matrice)
    
    matrice = [1,2,3,0,0,0,0,0;1,2,3,4,5,0,0,0];
    validateattributes(matrice,{'double'},{'2d','nonempty'})

    [m,n] = size(matrice);
 
    o = 0 ; 

    for i = 1 : m 
        for j = 1 : n

            if matrice(m,n) == 0
                o = o + 1;
            end

        end
    end
    fprintf('%d',o);
end

For some reason my variable o increments everytime...even if the number is not zero. I'm kinda of a newbie so I don't know what is the problem. please help.

Answer 1

[Jan]

Replace

if matrice(m,n) == 0

by

if matrice(i,j) == 0

Currently you are checking the last element of the matrix in each iteration.

A standard method to examine such problems is to add some output of the currently processed element to the command window.

By the way, the singular of "matrices" is "matrix".

Some matlabish way to count the zero elements: [EDITED, thanks Image Analyst!]

sum(A(:) == 0)
numel(A) - nnz(A)

[DGM]

matrice creuse : sparse matrix

... not that I'm any authority on other languages. That's just what I get when I point my translator plugin at it.

[Image Analyst]

For the second one, I assume you meant

numNonZeros = nnz(A)

[Jan]

@Image Analyst: The OP counts the number of zeros, so numel(A)-nnz(A) is correct. Or nnz(~A) .

[Image Analyst]

OK, but at the end of your comment you said:

"Some matlabish way to count the non-zero elements:"

sum(A(:) == 0)
numel(A) - nnz(A)

"nnz(A)" is the number of non-zeros, not "numel(A)-nnz(A)"

That's what I was referring to.

I guess you really meant "Some matlabish way to count the zero elements:"

[Jan]

Ah, yes. Thanks. I've fixed it.

Answer 2

[Image Analyst]

Get rid of this line

matrice = [1,2,3,0,0,0,0,0;1,2,3,4,5,0,0,0];

because it just blows away any matrix you pass in via the argument list.

Also you're using the wrong indexes in

if matrice(m,n) == 0

That just looks at the very last element in the lower right corner of the matrix.

It should be

if matrice(j, i) == 0

Plus you're never assigning nbDeZero. You need to do

nbDeZero = o;

at the end of the function. Also don't use o as the variable name because it looks too much like 0. Use numNonZeros or some other descriptive variable name.