16.4 Floating-Point Arithmetic: Caveat Emptor!

Math class is tough!

Teen Talk Barbie, July 1992

This section provides a high-level overview of the issues involved when doing lots of floating-point arithmetic.100 The discussion applies to both hardware and arbitrary-precision floating-point arithmetic.

CAUTION: The material here is purposely general. If you need to do serious

computer arithmetic, you should do some research first, and not rely just on what we tell you.

Inexactness of computations    Floating point math is not exact.
Getting Accuracy    Getting more accuracy takes some work.
Try To Round    Add digits and round.
Setting precision    How to set the precision.
Setting the rounding mode    How to set the rounding mode.

Footnotes

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There is a very nice paper on floating-point arithmetic by David Goldberg, “What Every Computer Scientist Should Know About Floating-Point Arithmetic,” ACM Computing Surveys 23, 1 (1991-03): 5-48. This is worth reading if you are interested in the details, but it does require a background in computer science.