diagonal matrix with ones

Hello I am trying to do a diagonal inferior matrix with a diagonal of ones but my diagonal have differentes valors. How do i do a matrix with diagonal of ones? Here is my code:

if true
  % code
a=[6,9,7;6,2,0;1,8,3]
a=tril(a)
end

[Daniel Shub]

What would be really helpful is if in addition to your example input you could tell us what you want the output to be.

Answer 1

[Sean de Wolski]

eye(5)

?

more per clarification:

a = tril(magic(3));
a(logical(eye(size(a,1)))) = 1

Answer 2

[Cristian]

Hello Thanks for the answers but the firs answer just create a matriz of 5x5 with diagonal of ones and I need my matrix "a" but with diagonal of ones. The second answer has an error say: ??? Undefined function or variable 'n'.

Error in ==> Untitled2 at 3 [ii,jj]=ind2sub(size(a),1:n*m)

What should I do?

Thanks

[Sean de Wolski]

see more in my answer above.

Answer 3

[Leah]

a(eye(3))=1;

like that?

[Sean de Wolski]

You need the logical() around eye() or it will error.

[Leah]

thanks Sean, I'm waiting on my license at my new job :)

[Sean de Wolski]

I'm sure your friendly sales rep would be happy to set you up with a trial :) !

Answer 4

[Cristian]

Well thaks Azzi Abdelmalek but now with your code matlab give me a triangular matrix with ones down of the diagonal and I need my diagonal just of ones. I could divide the last coefficent each row, and so have my diagonal with ones but I dont know manipulate rows and how I do that. Example I want that my triangular matrix: A=[6,9,7;6,2,0;1,8,3] A=tril(A)

A=[6,0,0;6,2,0;1,8,3]---->A=[1,0,0;3,1,0;1/3,8/3,1] This I want to do, having any matrix.

[Sean de Wolski]

See my more section. Where'd the 1/3 and the 8/3 come from?

[Cristian]

That comes of divide by 3 all the third row to have my last coefficent with 1

Answer 5

[Matt J]

 n=size(a,1);
 a(1:n+1:end)=1;

Answer 6

[Miroslav Balda]

Your last comment explained how to construct the resulting matrix. You see, how important it is to precisely formulate your question.

       Anew = diag(1./diag(A))'*tril(A)

Answer 7

[Miroslav Balda]

There is even simpler solutionof your problem:

       Anew = diag(diag(A))\tril(A)