Re: least square solution of b = A * x with a very huge A matrix

[c.]

On 29 May 2013, at 15:26, andrea console <address@hidden> wrote:

> Hi to all,
> I'm not a mathematician, but I have to solve this A*x=b problem. Since I'm 
> working with high resolution "fit" files (images), the related matrices are 
> very huge but sparse. I tried x = A\b, but it  gives the error: "SparseQR: 
> sparse matrix QR factorization filled" that I don't understand.
> Additional informations: 
> "A" matrix is a matrix of square matrices, n*3 matrices: for each row, the 
> first is a diagonal one, the second is simply sparse and the third is an eye 
> matrix. However, since I have to eliminate saturated pixel, I delete some 
> rows before computation.
> I'm working with Octave 3.6.4

Hi,
I am not sure I understand your description completely, 
is your matrix square or rectangular? how many rows, columns and non zero 
elements does it have?
c.