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Java's new Floating-point math

Jan 17, 2009, 22:03 (0 Talkback[s])
(Other stories by Elliotte Rusty Harold)

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"Version 5 of the Java Language Specification added 10 new methods to java.lang.Math and java.lang.StrictMath, and Java 6 added another 10. Part 1 of this two-article series looked at the new methods that make sense mathematically. That is, they provide functions that a pre-computer-era mathematician would find familiar. Here in Part 2, I focus on the functions that make sense only when you realize that they're designed for operating on floating-point numbers instead of abstract real numbers.

"As I noted in Part 1, the distinction between a real number such as e or 0.2 and its computer representation such as a Java double is an important one. The Platonic ideal of the number is infinitely precise, whereas the Java representation has only a fixed number of bits (32 for a float, 64 for a double) to work with. The maximum value of a float is about 3.4*1038, which isn't large enough for some things you might wish to represent, such as the number of electrons in the universe."

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