when I run this code I get Undefined function or variable 'U'.

for i=1:n       
    h=u(1:n,i:i);
    b=a(i,1);
    if b>0.0001
     U(1:n,i:i)=h/sqrt(b);
    end     
end
[N,M]=size(U);

[Jan]

By the way, i:i is a waste of time. Use i only.

Answer 1

[Bruno Luong]

MATLAB makes distinction between upper case and lower case in variable name. If you call

[u,d,v]=svd(K);

then you have to use small u afterwards, or the opposite.

[Rui Mauaie]

I already got the answer I changed the type of letter but I got the same error, thanks.

[Stephen23]

@Rui Mauaie: please show us the complete code that you used.

[Jan]

@Rui Mauaie: And a copy of the complete error message.

[Bruno Luong]

He also deleted the code he posted previously making my comment difficult to understand.