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changeset 7522:8a6965a01176

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log2: ensure F strictly less than 1
author John W. Eaton <jwe@octave.org>
date Sun, 24 Feb 2008 03:32:49 -0500
parents 6f10bbb2854a
children f2000f1971ab
files doc/interpreter/contributors.in scripts/ChangeLog scripts/specfun/log2.m
diffstat 3 files changed, 13 insertions(+), 1 deletions(-) [+]
line wrap: on
line diff
--- a/doc/interpreter/contributors.in	Sun Feb 24 02:58:01 2008 -0500
+++ b/doc/interpreter/contributors.in	Sun Feb 24 03:32:49 2008 -0500
@@ -59,10 +59,11 @@
 Peter Gustafson
 Kai Habel
 William P. Y. Hadisoeseno
+Jaroslav Hajek
 Benjamin Hall
 Kim Hansen
 Soren Hauberg
-Jaroslav Hajek
+Dave Hawthorne
 Daniel Heiserer
 Yozo Hida
 Roman Hodek
--- a/scripts/ChangeLog	Sun Feb 24 02:58:01 2008 -0500
+++ b/scripts/ChangeLog	Sun Feb 24 03:32:49 2008 -0500
@@ -1,3 +1,8 @@
+2008-02-24  John W. Eaton  <jwe@octave.org>
+
+	* specfun/log2.m: Ensure returned value of F strictly less than 1.
+	From Dave Hawthorne <davehawthorne@ieee.org>.
+
 2008-02-22  Ben Abbott  <bpabbott@mac.com>
 
 	* specfun/legendre.m: Doc fix.
--- a/scripts/specfun/log2.m	Sun Feb 24 02:58:01 2008 -0500
+++ b/scripts/specfun/log2.m	Sun Feb 24 03:32:49 2008 -0500
@@ -53,6 +53,12 @@
     f = abs (x) + (x == 0);
     e = (floor (log (f) / log (2)) + 1) .* (x != 0);
     f = sign (x) .* f ./ (2 .^ e);
+    ## Workaround to cases of f == 1 (due to precision issues).
+    idx = abs (f) >= 1;
+    if (any (idx))
+      f(idx) /= 2;
+      e(idx)++;
+    endif
   else
     error ("log2 takes at most 2 output arguments");
   endif