SVD and RREF don't give same result

Hi All,

I am having a problem with SVD. The function rref works fine for solving a set of overdefined linear equations AX=b; but I am having a trouble to get the same result using SVD.

For rref, i was using the synatx solution=rref([A,b]) and it gave correct result

For SVD, i was using the syntax [u, s, v]=svd(A,0) and then solution=v*((u'*b)./diag(s))

However, the solutions are completely different. What should I do for achieving the same result

Thanks in advance Sudipta

[Matt J]

Beware RREF. It was designed for classroom use only, as discussed here

http://www.mathworks.com/matlabcentral/newsreader/view_thread/263993#689500

and not for serious problem solving. I don't know if they've made it more robust since then, but I doubt it.

[Matt J]

However, the solutions are completely different. What should I do for achieving the same result

Convince us that this really happens. Attach a .mat file with your A,b data so we can try to reproduce what you see.

[Sudipta Sinha]

Thank you very much for your answer. I appreciate it. Please find the attached file. The matrix A, b and some associated results are there. please have a look on it

[Matt J]

That is not a .mat file. It appears to be a text file. It also appears to be a duplicate of the data you provided in this post

http://www.mathworks.com/matlabcentral/answers/130571-problem-with-rref-function

which we already know is not over-determined.

[Sudipta Sinha]

yes, that is my data. i need to solve this one. none of the methods are giving reasonable result. how do i generate a .mat file

[Matt J]

Use the SAVE command to save variables to a .mat file (and the LOAD command to reload them).