From: Taylor R Campbell <campbell@mumble.net>
Date: Thu, 25 Oct 2018 04:57:30 +0000 (+0000)
Subject: Fix stray line, clarify, and simplify.
X-Git-Tag: mit-scheme-pucked-10.1.2~16^2~170
X-Git-Url: https://birchwood-abbey.net/git?a=commitdiff_plain;h=dc2aa86d88cd967db97453096f4434b987d5267b;p=mit-scheme.git

Fix stray line, clarify, and simplify.
---

diff --git a/src/runtime/arith.scm b/src/runtime/arith.scm
index 665dd5e48..ba1753a11 100644
--- a/src/runtime/arith.scm
+++ b/src/runtime/arith.scm
@@ -2063,13 +2063,13 @@ USA.
          ;; raise inexact and underflow here.)
          0.)
 	((<= x -37)
-         ;; e^x < eps/2, so
+         ;; e^x < eps, so
          ;;
          ;;     |e^x - e^x/(1 + e^x)|/|e^x/(1 + e^x)|
          ;;     <= |1 - 1/(1 + e^x)|*|1 + e^x|
+         ;;      = |(1 + e^x - 1)/(1 + e^x)|*|1 + e^x|
          ;;      = |e^x/(1 + e^x)|*|1 + e^x|
-         ;;      = |e^x/(1 + e^x) + e^x|
-         ;;     <= |e^x + e^x|
+         ;;      = |e^x|
          ;;      < eps.
          ;;
          (exp x))