How to check if everything below the column is zero

I have a matrix,

[1 2 3; 0 1 0; 0 1 1]

And I want to check if everything below a certain element is zero. For example, at A(2, 2) the element below is not zero so I want to output false. I have the following

idy=1:size(A,1)<i %rows less than i
if  all(A(i,idy)==0)
     x=true;
end

However, I do not believe it's right, can anyone help me fix it please. Thanks!

[Walter Roberson]

x = ~any( A(i,i+1:end) );

would be more compact.

[Natalie Murawski]

A = [1 2 3 4 ;0 1 2 3; 0 0 0 0]
i=1
x=~any(A(i,i+1:end));
x

I get that it is 0, false, shouldn't it be 1, true, as there is nothing below the first row.

[Walter Roberson]

x = ~any( A(i+1:end, i) );

[Natalie Murawski]

Thank you! It works!