JDK-4406429 : RFE: Add IEEE 754 Recommended Functions to Math, StrictMath
  • Type: Enhancement
  • Component: core-libs
  • Sub-Component: java.lang
  • Affected Version: 1.3.0,5.0
  • Priority: P4
  • Status: Closed
  • Resolution: Duplicate
  • OS: generic
  • CPU: generic
  • Submitted: 2001-01-19
  • Updated: 2005-10-25
  • Resolved: 2005-10-25
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Name: yyT116575			Date: 01/19/2001

~/project/visMineBench>java -version
java version "1.3.0"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.3.0-C)
Java HotSpot(TM) Client VM (build 1.3.0-C, mixed mode)

Java should incorporate the following methods into java.lang.Math:

      copySign(x,y)  returns x with the sign of y.
      scalb(y,n)     returns y * 2n for integers n without
                     explicitly computing 2n.
      nextAfter(x,y) returns the next representable neighbor of x in the
                     direction towards y.
      unordered(x,y) Returns true is one of its arguments is unordered
                     with respect to the other.
                     This occurs when at least one is a NaN.
      fpClass(x)     Returns an integer that indicates which of the
                     nine "kinds" of IEEE floating-point numbers x is.
      logb(x)        Returns the unbiased exponent of x.

These descriptions are copied from:

It also says there that IEEE 754 recommends these methods.
(Review ID: 115478) 

EVALUATION The fix for bug 4826652 added the following methods to the Math and StrictMath classes: copySign getExponent nextAfter nextUp scalb These methods constitute the majority of the functionality requested in this bug. (In my estimation, a raw getExponent is more useful than logb.) Therefore, this bug will be closed as a duplicate of 4826652; bug 6341163 will track the remaining unimplemented minor functionality, like fpClass and unordered, as well as additional recommended functionality added by the 754 revision committee.

EVALUATION It is too late to get these methods into Merlin (I tried); they should be added in the next major Java release. joe.darcy@eng 2001-03-27 Trying for Tiger release; will track developments in IEEE 754 revision committee. ###@###.### 2002-05-31 Not approved for Tiger. ###@###.### 2003-05-08