Re: [adoptium-wg] Question about Adoptium Java 17 and Floating Point.

[Tim Ellison <t.p.ellison@xxxxxxxxx>]

Hi.

This is not the correct list for such questions, as the working group 
only looks after the governance of Adoptium - not the technical work.

The short answer is that Adoptium Temurin builds the unmodified OpenJDK 
code that implements the Java language spec. That spec requires floats 
and doubles to adhere to IEEE754 behavior, you can use BigDecimal for 
arbitrary precision arithmetic...


$ docker run -it eclipse-temurin:17
Nov 19, 2021 10:58:20 AM java.util.prefs.FileSystemPreferences$1 run
INFO: Created user preferences directory.
|  Welcome to JShell -- Version 17.0.1
|  For an introduction type: /help intro

jshell> 0.1f*0.1f
$1 ==> 0.010000001

jshell> 0.1d*0.1d
$2 ==> 0.010000000000000002

jshell> new BigDecimal("0.1").multiply(new BigDecimal("0.1"))
$3 ==> 0.01


Please direct any follow-ups to the Adoptium Slack channel via
https://adoptium.net/slack.html

or the OpenJDK core-libs mailing list via
https://mail.openjdk.java.net/mailman/listinfo/core-libs-dev


Thanks,
Tim


On 19/11/2021 05:36, A Z wrote:
> I would like to know how Adoptium Java performs.
>
> -Is it compatible with Free Open Source Java libraries,
> or other Java libraries, out there?
>
> -Has Adoptium removed the phenomenon of Java
> Floating Point denormal and pronormal values?
> Consider the following Java code snippet:
>
> **//----------------------------------------------------------
> package JavaApplication;
> import static java.lang.System.*;
> public class Start
> {
>      public static void main(String ...args)
>      {
>      out.println("Program has started...");
>      double a = 0.1;
>      double b = 0.1;
>      double c = a*b;
>      out.println();
>      out.println(c);
>      out.println();
>      out.println(c == 0.01);
>      float d = 0.01F;
>      float e = 0.01F;
>      float f = d*e;
>      out.println();
>      out.println(f);
>      out.println();
>      out.println(f == 0.01);
>      out.println();
>      out.println("Program has Finished.");
>      }}
> //----------------------------------------------------------**
>
> -What I need is a version of Java 17 that has the same
> free-for-all-use license model as OpenJDK17, but has
> removed the phenomenon of denormal and pronormal
> values, of all defaulting arithmetic, systematically,
> involving float and double, and their objects.
>
> -Will Adoptium run the included code fragment,
> outputting the generally expected results,
> printing true and not false?
>
>
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