numpy (matrix solver) - python vs. matlab

[Nasser M. Abbasi]

On 04/29/2012 07:17 PM, someone wrote:

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

There are things you can see right away about a matrix A being singular 
without doing any computation. By just looking at it.

For example, If you see a column (or row) being a linear combination of 
other column(s) (or row(s)) then this is a no no.

In your case you have

      1     2     3
      11    12    13
      21    22    23

You can see right away that if you multiply the second row by 2, and 
subtract from that one times the first row, then you obtain the third row.

Hence the third row is a linear combination of the first row and the 
second row. no good.

When you get a row (or a column) being a linear combination of others 
rows (or columns), then this means the matrix is singular.

--Nasser