Class Notes

• First day: generic stuff, and timing calling functions with differing numbers of elements.
• Some general software tools of interest and use. The material is valid and will suffice for this course, but it is cursory at best and you should hunt down more advanced examples. Use your Google-fu.
  1. Most of your assignments will involve writing code that is used to generate some results: timings of different approaches, etc. Using makefiles will ease the job of this writing and running, and I will in some cases require this. Makefiles are the standard mechanism for building complex software systems, not just in scientific computing. An example of using makefiles is in the simple timing function code examples. Download the tar file that has both C and Fortran examples
  2. Accessing remote machines is dangerous if you send passwords in the clear. Use this introduction to SSH to learn how to set up a more secure way of transfering files, and especially for opening windows from a remote machine on a local console. The CS department's systems staff has more up-to-date notes showing how to use OpenSSH, which is now a campus standard. They also have other platform notes about using SSH from a web browser or Windows.
• Timing things on a computer. The five pages listed have large images and some linked data sets. It's easy to scale down or zoom out from a large image, but not possible to zoom in and still have good resolution (unless you use some SVG format). Still, don't send these off to a printer without first looking at them. Better yet, don't send these off to a printer at all; the Web pages will be updated as needed.
  1. General notes about timings
  2. Using Unix rusage() data
  3. Finding clock resolution, and what to do with it
  4. How to time simple operations like integer addition, double precision multiply, etc. This was not covered in class, and you can safely ignore it ... unless you find it interesting
  5. Code examples for using a timer, in both C and Fortran
• Basic computer architecture
  1. General architecture ideas
  2. Memory systems, which includes material not covered in class, e.g., cache policies.
  3. Notes about compiler optionss
  4. Pipelining
  5. Examples
  6. Finding and using cacheline size
  7. Block matrix-matrix multiplication
  8. The BLAS
  9. The BLAS, part 2
  10. General notes about numerical linear algebra
  11. General notes about LU factorization
  12. Pivoting and triangular solves
  13. Deriving a BLAS-3 version
  14. Error bounds for LU method
• Basic Matlab operations
  1. Matlab Introduction
  2. Matlab Resources Help Facilities
  3. Data Entry in Matlab
  4. Matlab Array Notation and Operations
  5. Genreal Advice about Matlab Hacking
  6. The Plot Thickens
  7. Matlab M-files
• Fortran
  1. Fortran Slides (PDF)
• BLAS
  1. blasqr.pdf
• Linear least squares problems
  1. General properties of linear least squares (LLS) problems
  2. Some methods for solving LLS
  3. The singular value decomposition (SVD)
  4. The QR factorization using Givens rotations>
  5. The QR factorization using Householder reflectors
  6. A block QR factorization

1. Started: Wed 31 Aug 2011, 07:58 AM
2. Modified: 11 Sep 2011 to add notes about software tools
3. Modified: Tue 13 Sep 2011, 11:41 AM to add notes about timing and computer architecture
4. Modified: Mon 10 Oct 2011, 11:40 AM to add notes about Matlab
5. Modified: Wed 12 Oct 2011, 08:05 AM
6. Modified: Wed 12 Oct 2011, 08:05 AM to add notes about LU to the "architecture" section
7. Modified: Wed 26 Oct 2011, 08:32 AM to add Fortran and Blas PDFs
8. Modified: Mon 21 Nov 2011, 06:39 PM adding the LLS notes
9. Last Modified: Mon 21 Nov 2011, 06:39 PM