From 3c1572ddb43ba7f4cbae57ee4b019a2cd45ee015 Mon Sep 17 00:00:00 2001
From: drh <>
Date: Thu, 17 Nov 2022 14:40:33 +0000
Subject: [PATCH] Use the log10() and log2() functions from the standard C
 library to implement the equivalent SQL functions, in the hope that this will
 prevent reported precision problems. See
 [forum:/forumpost/cfceb1230bdcfd84|forum post cfceb1230bdcfd84] and the
 surrounding thread.

FossilOrigin-Name: 7c572d02e60a83b36543ba4d9d45f61e9fc111b61fee085410c2d87558c732d6
---
 manifest      | 12 ++++++------
 manifest.uuid |  2 +-
 src/func.c    |  8 +++-----
 3 files changed, 10 insertions(+), 12 deletions(-)

diff --git a/manifest b/manifest
index 65bffb3672..2432894ab6 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Split\sout\sthe\sdocumentation\sfor\ssqlite3_value_encoding()\sinto\sits\sown\npage\sand\smake\sit\sclear\sthat\sthis\sinterface\sis\sintended\sfor\stesting\sand\ndebugging\sonly.\n[forum:/forumpost/c9f445453da950ad|Forum\sthread\sc9f445453da950ad].\nComment\schanges\sonly\s-\sno\schanges\sto\scode.
-D 2022-11-17T13:58:25.001
+C Use\sthe\slog10()\sand\slog2()\sfunctions\sfrom\sthe\sstandard\sC\slibrary\sto\simplement\nthe\sequivalent\sSQL\sfunctions,\sin\sthe\shope\sthat\sthis\swill\sprevent\sreported\nprecision\sproblems.\nSee\s[forum:/forumpost/cfceb1230bdcfd84|forum\spost\scfceb1230bdcfd84]\sand\sthe\nsurrounding\sthread.
+D 2022-11-17T14:40:33.537
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -590,7 +590,7 @@ F src/delete.c 86573edae75e3d3e9a8b590d87db8e47222103029df4f3e11fa56044459b514e
 F src/expr.c 847f87d9df3ede2b2b0a8db088af0b9c1923b21009f8ea1b9b7b28cb0a383170
 F src/fault.c 460f3e55994363812d9d60844b2a6de88826e007
 F src/fkey.c 722f20779f5342a787922deded3628d8c74b5249cab04098cf17ee2f2aaff002
-F src/func.c d25f3c667d59dbac195e65f3539fdbbd8a36c142ce7bcdb45d1baf07446ad13a
+F src/func.c 7e86074afc4dc702691a29b7801f6dcc191db092b52e8bbe69dcd2f7be52194d
 F src/global.c e06ff8e0acd85aec13563c9ecb44fbbf38232ccf73594998fd880b92d619594b
 F src/hash.c 8d7dda241d0ebdafb6ffdeda3149a412d7df75102cecfc1021c98d6219823b19
 F src/hash.h 3340ab6e1d13e725571d7cee6d3e3135f0779a7d8e76a9ce0a85971fa3953c51
@@ -2055,8 +2055,8 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P a119a9e2ade4eac5feb1aa885c15b83e725f87386351de99d3abb49656219d50
-R b081909c6ecb1750561be5091dea8e63
+P 9048a766ff7dfa0cd91ea74092e462f4501cb3f719033ccb55700bf5e4dfd0d3
+R a034e1e03397012452b518f4075f2764
 U drh
-Z c8051a67682b7cc2de89c2c47da25213
+Z 49084f227abbaddd45e0c2d870d50ee7
 # Remove this line to create a well-formed Fossil manifest.
diff --git a/manifest.uuid b/manifest.uuid
index 4a06fb59e5..d717acf28e 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-9048a766ff7dfa0cd91ea74092e462f4501cb3f719033ccb55700bf5e4dfd0d3
\ No newline at end of file
+7c572d02e60a83b36543ba4d9d45f61e9fc111b61fee085410c2d87558c732d6
\ No newline at end of file
diff --git a/src/func.c b/src/func.c
index b42b2588af..3c5a852307 100644
--- a/src/func.c
+++ b/src/func.c
@@ -2106,17 +2106,15 @@ static void logFunc(
     }
     ans = log(x)/b;
   }else{
-    ans = log(x);
     switch( SQLITE_PTR_TO_INT(sqlite3_user_data(context)) ){
       case 1:
-        /* Convert from natural logarithm to log base 10 */
-        ans /= M_LN10;
+        ans = log10(x);
         break;
       case 2:
-        /* Convert from natural logarithm to log base 2 */
-        ans /= M_LN2;
+        ans = log2(x);
         break;
       default:
+        ans = log(x);
         break;
     }
   }
-- 
2.47.2