20.11

java.lang.Math

THE PACKAGE JAVA.LANG

To ensure portability of Java programs, the specifications of many of the

numerical functions in this package require that they produce the same results as

certain published algorithms. These algorithms are available from the well known

network library

netlib

 as the package

fdlibm

 ( Freely Distributable Math

Library ). These algorithms, which are written in the C programming language,

are to be understood as if executed in Java execution order with all floating point

operations following the rules of Java floating point arithmetic.

The network library may be found at

http://netlib.att.com

 on the World

Wide Web; then perform a keyword search for

fdlibm

. The library may also be

retrieved by E mail; to begin the process, send a message containing the line:

send index from fdlibm

to

netlib@research.att.com

. The Java math library is defined with respect to

the version of

fdlibm

 dated 95/01/04. Where

fdlibm

 provides more than one def 

inition for a function (such as

acos

), the  IEEE754 core function  version is to be

used (residing in a file whose name begins with the letter

e

).

A complete and self contained description of the algorithms to be used for

these functions will be provided in a future version of this specification. It is also

anticipated that the algorithms will be coded in Java to provide a reference imple 

mentation that is not tied to

fdlibm

.

20.11.1

public static final double E = 2.7182818284590452354;

The constant value of this field is the

double

 value that is closer than any other

to

e

, the base of the natural logarithms.

20.11.2

public static final double PI = 3.14159265358979323846;

The constant value of this field is the

double

 value that is closer than any other

to

, the ratio of the circumference of a circle to its diameter.

20.11.3

public static double sin(double a)

This method computes an approximation to the sine of the argument, using the

sin

 algorithm as published in

fdlibm

 (see the introduction to this section).

Special cases:

If the argument is NaN or an infinity, then the result is NaN.

If the argument is positive zero, then the result is positive zero; if the argu 

ment is negative zero, then the result is negative zero.

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