You are viewing a plain text version of this content. The canonical link for it is here.
Posted to issues@commons.apache.org by "Alex Herbert (Jira)" <ji...@apache.org> on 2020/03/24 23:32:00 UTC
[jira] [Commented] (NUMBERS-143) Investigate Math.hypot for
computing the absolute of a complex number
[ https://issues.apache.org/jira/browse/NUMBERS-143?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17066265#comment-17066265 ]
Alex Herbert commented on NUMBERS-143:
--------------------------------------
A custom hypot implementation has been added to Complex. This uses the method of Dekker for the high precision sum.
commit: 643e1693b7ba06aa3cc524fb8b83a983a62a6227
> Investigate Math.hypot for computing the absolute of a complex number
> ---------------------------------------------------------------------
>
> Key: NUMBERS-143
> URL: https://issues.apache.org/jira/browse/NUMBERS-143
> Project: Commons Numbers
> Issue Type: Task
> Components: complex
> Reporter: Alex Herbert
> Priority: Minor
> Time Spent: 40m
> Remaining Estimate: 0h
>
> {{Math.hypot}} computes the value {{sqrt(x^2+y^2)}} to within 1 ULP. The function uses the [e_hypot.c|https://www.netlib.org/fdlibm/e_hypot.c] implementation from the Freely Distributable Math Library (fdlibm).
> Pre-java 9 this function used JNI to call an external implementation. The performance was slow. Java 9 ported the function to native java (see [JDK-7130085 : Port fdlibm hypot to Java|https://bugs.java.com/bugdatabase/view_bug.do?bug_id=7130085]).
> This function is used to define the absolute value of a complex number. It is also used in sqrt() and log(). This ticket is to investigate the performance and accuracy of \{{Math.hypot}} against alternatives for use in Complex.
>
--
This message was sent by Atlassian Jira
(v8.3.4#803005)