0_overview

Harvard Applied Math 205: Code Examples

Unit 0: Overview of Scientific Computing

acc_test.py

This program tests the value of machine epsilon, by comparing how small a value of h is needed before 1+h evaluates to the same as 1.

acc_test.cc

This is a version of acc_test.py written in C++. With the GNU C++ compiler, the program can be compiled with

g++ -o acc_test acc_test.cc

and then run with

./acc_test

It finds the same value of h as the Python version, emphasizing that what is being tested is due to the hardware-level implementation of floating point arithmetic, as opposed to being due to the specific programming language.

paranoia.c

The lectures also discussed paranoia.c, originally written by Prof. William Kahan (UC Berkeley), available here:

http://www.netlib.org/paranoia/paranoia.c

This C program performs a number of tests to ensure that the computer's arithmetic system does not have any errors.