You will need to do parts 2 and 3 of this assignment using your SUN Unix account:
if you still don't have one, request one ASAP (from petagna@cs if you are registered
in G22.2420 and the math department if you are registered in G63.G22.2420).
The Legendre polynomials make a good test case. Make sure you use a large
enough n and m to make the comparsion meaningful (at least m=500, and go
higher until it starts to take too long to wait), but but start with smaller
values until you are sure everything is working.
Plot your results
on nicely labelled plots over a range of test sizes, using different
plotting symbols for different codes (type "help plot").
Measure the times using cputime .
(Elapsed time measures obtained by "etime" or "tic; ... toc"
are affected by how much work other users are doing on the same machine).
Measure accuracy with norm(Q'*Q - I) and norm(A - Q*R).
Make some written comments which draw conclusions from the results.
If you want to use Java instead of C or Fortran, which has the attraction of avoiding the MEX interface altogether, you may do so, but you are on your own as far as the details go. In order to use the BLAS, you would need either to to call the C or Fortran compiled versions using the Java Native Interface or download Java versions of the BLAS from the web.
Some of you may find this homework very difficult. The key is to carefully look at the files available on the web and, once you understand them, make the necessary changes. Don't try to code from scratch! If you are lost, don't hesitate to contact me and discuss things - the sooner, the better. Don't panic, eventually you will get it!
I will be out of town again Wed-Fri this week, but available this Tuesday and all of next week.