What is a function that takes the diagonal of a matrix (N) and converts the diagonal to all zeros.

Ex.

>> m=[1 2 3; 4 5 6;1 2 3]

m =

     1     2     3
     4     5     6
     1     2     3

>> m=diagzero (m)

m =

     0     2     3
     4     0     6
     1     2     0

Answer 1

[Youssef Khmou]

try :

 function Y=diagzero(X)

 N=size(X);
 if N(1)~=N(2)
 error(' Matrix not square');
 end
 Y=X;
 for x=1:N(1)
   Y(x,x)=0;
 end

Answer 2

[James Tursa]

Another method if you know m is square:

    r = size(m,1) + 1;
    m(1:r:end) = 0;

If you don't know if m is square or not you could do this:

    r = size(m,1);
    n = min(numel(m),r*r);
    m(1:r+1:n) = 0;

Answer 3

[Andrei Bobrov]

m(eye(size(m))>0) = 0;

[James Tursa]

Or to avoid testing all those 0's:

m(speye(size(m))>0) = 0;

or:

m(logical(speye(size(m)))) = 0;

Answer 4

[Azzi Abdelmalek]

ii=1:size(m,1);
m(sub2ind(size(m),ii,ii))=0

Answer 5

[Jonathan Epperl]

Assuming m is square (because else you'd have to define the diagonal for me):

diagzero = @(m) m - diag(diag(m));

[James Tursa]

Doesn't work on any diagonal elements that are inf or nan.