* iterative solution of large sparse systems*

J.M. Melenk

Some desasters attributable to poor numerics.

A few software bugs with consequences

Wednesdays 13:00-15:00, SEM 101C (4. Stock, gruener Turm)

class notes are handed out as we go along:

To download these files right click on the link and choose 'Save target as'. Select the directory you wish to download the file to and change the 'Save as type' box to 'All files' otherwise '.txt' wil be tagged onto the filename.

The following matrices have been downloaded from the Matrix Market. The matrices are stored in the Matrix Market file format which can be read using the mmread M-file. This file and the matrix data needs to be in the same directory (or the path changed accordingly) as your script/file.

To read in a matrix to the variable A simply include

A=mmread('matrix_name.mtx')

in your script/function. Note A will be defined to be sparse - you don't need to do anything else

- Symmetric Positive Definite Matrices:

- nos4.mtx - 100x100 estimated condition number 2.7x10^3. Matrix Market Page
- Matrix Market Page
- nos6.mtx - 675x675 estimated condition number 8x10^6. Matrix Market Page
- bcsstk14.mtx - 1806x1806 estimated condition number 1.3x10^10. Matrix Market Page

- Non-symmetric Matrices:

- gre__185.mtx - 185x185 estimated condition number 5.1x10^5. Matrix Market Page
- steam1.mtx - 240x240 estimated condition number 3x10^7. Matrix Market Page
- pores_3.mtx - 532x532 estimated condition number 6.6x10^5. Matrix Market Page
- sherman2.mtx - 1080x1080 estimated condition number 1.4x10^12. Matrix Market Page