[petsc-users] LU Decomposition

[Hong Zhang]

Nemanja,

Petsc LU solver for seqdense is a wrapper of LAPACK's routines (see
src/mat/impls/dense/seq/dense.c).
For Petsc's sparse LU, the diagonals are inverted.

Hong

On Wed, Aug 11, 2010 at 12:05 PM, Немања Илић (Nemanja Ilic)
<nemanja.ilic.81 at gmail.com> wrote:
> Hello,
>
> I figured this one myself :) As I was told in a previous email (thanks Barry), it depends on used Petsc's algorithm what will be the result of LU factoring. If matrix is created with MatCreateSeqDense and MatLUFactorSymbolic and MatLUFactorNumeric are used then the result matrix is simply "concatenated" L and U triangular matrices and elements on the diagonal are not inverted.
>
> regards,
> Nemanja
>
>
> On Tuesday 10 August 2010 17:52:53 Немања Илић (Nemanja Ilic) wrote:
>> Hello,
>>
>> Thank you very much, Hong and Barry. I managet to get inverse matrix following your advice! Could you tell me what are the elements of the result of LUFactor in respect to upper and lower triangular decomposition matrices? I know that elements on the diagonal are inverted.
>>
>> Thank you,
>> regards,
>> Nemanja
>>
>