[Gcl-devel] util.ht

[root]

The i-output.boot.pamphlet file has been modified to change the test slightly.
We add a simple fudge-factor as a temporary measure until log10 computes
correct values. The code was: 
    u < MOST_-POSITIVE_-LONG_-FLOAT => 1+negative+FLOOR LOG10 u
and is now:
    u < MOST_-POSITIVE_-LONG_-FLOAT => 1+negative+FLOOR ((LOG10 u) + 0.0000001)

The attached diff:

===========================================================================

--- i-output.boot.pamphlet      Sun Jul 20 15:10:37 2003
+++ i-output.boot.pamphlet.tpd  Sun Jul 20 15:12:16 2003
@@ -9,6 +9,26 @@
 \eject
 \tableofcontents
 \eject
+\section{GCL_log10_bug}
+In some versions of GCL the LOG10 function returns improperly rounded values.
+The symptom is:
+\begin{verbatim}
+(24) -> [1000]
+   (24)  [100]
+\end{verbatim}
+The common lisp failure can be shown with:
+\begin{verbatim}
+(25) -> )lisp (log10 1000)
+Value = 2.9999999999999996
+\end{verbatim}
+This previous boot code was:
+\begin{verbatim}
+    u < MOST_-POSITIVE_-LONG_-FLOAT => 1+negative+FLOOR LOG10 u
+\end{verbatim}
+and should be restored when the GCL bug is fixed.
+<<GCL_log10_bug>>=
+    u < MOST_-POSITIVE_-LONG_-FLOAT => 1+negative+FLOOR ((LOG10 u) + 0.0000001)
+@ 
 <<*>>=
 -- See LICENSE.AXIOM for Copyright
 
@@ -840,7 +860,7 @@
       negative := 0
     -- Try and be fairly exact for smallish integers:
     u = 0 => 1
-    u < MOST_-POSITIVE_-LONG_-FLOAT => 1+negative+FLOOR LOG10 u
+<<GCL_log10_bug>>
     -- Rough guess: integer-length returns log2 rounded up, so divide it by
     -- roughly log2(10). This should return an over-estimate, but for objects
     -- this big does it matter?