From: Taylor R Campbell <campbell@mumble.net>
Date: Sat, 27 Oct 2018 02:11:14 +0000 (+0000)
Subject: log1pexp(x) is never exactly x even if that's the best approximation.
X-Git-Tag: mit-scheme-pucked-10.1.2~16^2~145
X-Git-Url: https://birchwood-abbey.net/git?a=commitdiff_plain;h=528f857892781a7352980f81e303d95348417b62;p=mit-scheme.git

log1pexp(x) is never exactly x even if that's the best approximation.
---

diff --git a/src/runtime/arith.scm b/src/runtime/arith.scm
index ebe1e0ac4..ee2d0471f 100644
--- a/src/runtime/arith.scm
+++ b/src/runtime/arith.scm
@@ -2029,7 +2029,7 @@ USA.
 	((<= x flo:log-epsilon) (exp x))
 	((<= x 18) (log1p (exp x)))
 	((<= x 33.3) (+ x (exp (- x))))
-	(else x)))
+	(else (exact->inexact x))))
 
 ;;; Lemma 1.  If |d'| < 1/2, then |(d' - d)/(1 + d')| <= 2|d' - d|.
 ;;;