Bug ID: JDK-4929959 Clarify math library ulp accuracy requirements and hypot spec

Type: Bug
Component: core-libs
Sub-Component: java.lang
Affected Version: 5.0

Priority: P5
Status: Resolved
Resolution: Fixed
OS: generic
CPU: generic

Submitted: 2003-09-30
Updated: 2003-10-14
Resolved: 2003-10-14

Other
5.0 b24Fixed

The current phrasing in the discussion of the required accuracy of math library methods in terms of ulps could be improved.  Additionally the meaning of semi-monotonic for the two-argumetn hypot method should be explained.

CONVERTED DATA BugTraq+ Release Management Values COMMIT TO FIX: tiger tiger-beta FIXED IN: tiger tiger-beta INTEGRATED IN: tiger-b24 tiger-beta

14-06-2004

SUGGESTED FIX src/share/classes/java/lang>sccs sccsdiff -r1.63 -r1.64 Math.java ------- Math.java ------- 38,39c38,39 < * value is the difference between the two floating-point values < * closest to that numerical value. When discussing the accuracy of a --- > * value is the distance between the two floating-point values > * bracketing that numerical value. When discussing the accuracy of a 50,53c50,55 < * number, the exact result should be returned; otherwise, either of < * the two floating-point numbers which bracket the exact result may < * be returned. Besides accuracy at individual arguments, maintaining < * proper relations between the method at different arguments is also --- > * number, the exact result should be returned as the computed result; > * otherwise, either of the two floating-point values which bracket > * the exact result may be returned. For exact results large in > * magnitude, one of the endpoints of the bracket may be infinite. > * Besides accuracy at individual arguments, maintaining proper > * relations between the method at different arguments is also 95,96c97,98 < * A result must be within 1 ulp of the correctly rounded < * result. Results must be semi-monotonic. --- > * The computed result must be within 1 ulp of the exact result. > * Results must be semi-monotonic. 110,111c112,113 < * A result must be within 1 ulp of the correctly rounded < * result. Results must be semi-monotonic. --- > * The computed result must be within 1 ulp of the exact result. > * Results must be semi-monotonic. 127,128c129,130 < * A result must be within 1 ulp of the correctly rounded < * result. Results must be semi-monotonic. --- > * The computed result must be within 1 ulp of the exact result. > * Results must be semi-monotonic. 145,146c147,148 < * A result must be within 1 ulp of the correctly rounded < * result. Results must be semi-monotonic. --- > * The computed result must be within 1 ulp of the exact result. > * Results must be semi-monotonic. 161,162c163,164 < * A result must be within 1 ulp of the correctly rounded < * result. Results must be semi-monotonic. --- > * The computed result must be within 1 ulp of the exact result. > * Results must be semi-monotonic. 178,179c180,181 < * A result must be within 1 ulp of the correctly rounded < * result. Results must be semi-monotonic. --- > * The computed result must be within 1 ulp of the exact result. > * Results must be semi-monotonic. 227,228c229,230 < * A result must be within 1 ulp of the correctly rounded < * result. Results must be semi-monotonic. --- > * The computed result must be within 1 ulp of the exact result. > * Results must be semi-monotonic. 248,249c250,251 < * A result must be within 1 ulp of the correctly rounded < * result. Results must be semi-monotonic. --- > * The computed result must be within 1 ulp of the exact result. > * Results must be semi-monotonic. 273,274c275,276 < * A result must be within 1 ulp of the correctly rounded < * result. Results must be semi-monotonic. --- > * The computed result must be within 1 ulp of the exact result. > * Results must be semi-monotonic. 331c333 < * A result must be within 1 ulp of the correctly rounded result. --- > * The computed result must be within 1 ulp of the exact result. 469,470c471,472 < * A result must be within 2 ulps of the correctly rounded < * result. Results must be semi-monotonic. --- > * The computed result must be within 2 ulps of the exact result. > * Results must be semi-monotonic. 599,600c601,602 < * A result must be within 1 ulp of the correctly rounded < * result. Results must be semi-monotonic. --- > * The computed result must be within 1 ulp of the exact result. > * Results must be semi-monotonic. 1040,1041c1042 < * A result must be within 2.5 ulps of the correctly rounded < * result. --- > * The computed result must be within 2.5 ulps of the exact result. 1069,1070c1070 < * A result must be within 2.5 ulps of the correctly rounded < * result. --- > * The computed result must be within 2.5 ulps of the exact result. 1105,1110c1105,1110 < * A result must be within 2.5 ulps of the correctly rounded < * result. The result of <code>tanh</code> for any finite input < * must have an absolute value less than or equal to 1. Note that < * once the exact result of tanh is within 1/2 of an ulp of the < * limit value of ±1, correctly signed < * ±<code>1.0</code> should be returned. --- > * The computed result must be within 2.5 ulps of the exact result. > * The result of <code>tanh</code> for any finite input must have > * an absolute value less than or equal to 1. Note that once the > * exact result of tanh is within 1/2 of an ulp of the limit value > * of ±1, correctly signed ±<code>1.0</code> should > * be returned. 1135,1136c1135,1137 < * A result must be within 1 ulp of the correctly rounded < * result. Results must be semi-monotonic. --- > * The computed result must be within 1 ulp of the exact > * result. If one parameter is held constant, the results must be > * semi-monotonic in the other parameter. 1169,1170c1170,1171 < * A result must be within 1 ulp of the correctly rounded < * result. Results must be semi-monotonic. The result of --- > * The computed result must be within 1 ulp of the exact result. > * Results must be semi-monotonic. The result of 1210,1211c1211,1212 < * A result must be within 1 ulp of the correctly rounded < * result. Results must be semi-monotonic. --- > * The computed result must be within 1 ulp of the exact result. > * Results must be semi-monotonic. ###@###.### 2003-10-06

06-10-2003

EVALUATION A fine idea. ###@###.### 2003-09-29

29-09-2003

Relates :	JDK-4875088 - Clarify definition of 1-ulp accuracy
Relates :	JDK-4455590 - JavaDoc: comments for Math, StrictMath don't provide enough detail