[commons-numbers] branch master updated: Lower threshold for a ~ z

[ah...@apache.org]

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aherbert pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/commons-numbers.git


The following commit(s) were added to refs/heads/master by this push:
     new 45e6f56  Lower threshold for a ~ z
45e6f56 is described below

commit 45e6f56f310bafe478ce77e7d84439e21015e84d
Author: Alex Herbert <ah...@apache.org>
AuthorDate: Mon Dec 13 08:25:15 2021 +0000

    Lower threshold for a ~ z
    
    This threshold requires optimisation. The threshold was too high to pass
    existing tests in Commons Statistics (see STATISTICS-39).
---
 .../src/main/java/org/apache/commons/numbers/gamma/BoostGamma.java     | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/commons-numbers-gamma/src/main/java/org/apache/commons/numbers/gamma/BoostGamma.java b/commons-numbers-gamma/src/main/java/org/apache/commons/numbers/gamma/BoostGamma.java
index 0a5b9a1..ba11a7b 100644
--- a/commons-numbers-gamma/src/main/java/org/apache/commons/numbers/gamma/BoostGamma.java
+++ b/commons-numbers-gamma/src/main/java/org/apache/commons/numbers/gamma/BoostGamma.java
@@ -1824,8 +1824,7 @@ final class BoostGamma {
         double prefix;
         final double d = ((z - a) - Lanczos.gmh()) / agh;
 
-
-        if ((Math.abs(d * d * a) <= 100) && (a > 150)) {
+        if ((Math.abs(d * d * a) <= 100) && (a > 100)) {
             // special case for large a and a ~ z.
             // When a and x are large, we end up with a very large exponent with a base near one:
             // this will not be computed accurately via the pow function, and taking logs simply