changing diagional values with different values

Hello,

Is there any way to do the following:

let assume this is my matrix (MX1):

    x1    8    4    0
    4    x2    0    9
    1     0    x3   3
    0     3    0    x4
    

what I'm trying to do is the followin:

I should calculate each "x", where x = the summation of the values in the same row. for Exp: X1 = 8+4+0. [are there any way to automate this calculation?]

My idea is changing the x's diagonal to zeros to get the summation from, where the x will be zero. [I know how to do it]

then, generating a duplicated matrix and copy the calculated diagonal to the new matrix. [Is that possible ?] *this is must be automated because my matrix is 98*98

Thanks

Answer 1

[Star Strider]

I am not certain what result you want.

Try this:

MX1 = randi(9, 4)
D1 = diag(MX1);
Xv = sum(MX1,2) - D1;
MX1 = triu(MX1,1) + tril(MX1,-1) + diag(Xv)

Experiment to get the result you want.

[A Aln]

thank you so much, it works !!

[Star Strider]

As always, my pleasure!

Answer 2

[Fangjun Jiang]

n=5;
a=magic(n);
b=a;
index=sub2ind(size(a),1:n,1:n);
b(index)=0;
s=sum(b,2);
b(index)=s;