On 04/30/2012 02:57 AM, Paul Rubin wrote:

> someone<(E-Mail Removed)> writes:

>>> A is not just close to singular: it's singular!

>> Ok. When do you define it to be singular, btw?

>

> Singular means the determinant is zero, i.e. the rows or columns

> are not linearly independent. Let's give names to the three rows:

>

> a = [1 2 3]; b = [11 12 13]; c = [21 22 23].

>

> Then notice that c = 2*b - a. So c is linearly dependent on a and b.

> Geometrically this means the three vectors are in the same plane,

> so the matrix doesn't have an inverse.
Oh, thak you very much for a good explanation.

>>>> Which is the most accurate/best, even for such a bad matrix?

>

> What are you trying to do? If you are trying to calculate stuff

> with matrices, you really should know some basic linear algebra.
Actually I know some... I just didn't think so much about, before

writing the question this as I should, I know theres also something like

singular value decomposition that I think can help solve otherwise

illposed problems, although I'm not an expert like others in this forum,

I know for sure