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Overview
Comment:Update the FAQ to include an entry about binary versus decimal numbers. (CVS 2648)
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SHA1: 0bbe73fccfe52700c2ae1122388764e81a78bc22
User & Date: drh 2005-08-31 02:46:21
Context
2005-08-31
03:13
Refinements to the optimizer overview and integration into the website. (CVS 2649) check-in: ccd12e9e user: drh tags: trunk
02:46
Update the FAQ to include an entry about binary versus decimal numbers. (CVS 2648) check-in: 0bbe73fc user: drh tags: trunk
01:49
Adding the first cut of the optimizer overview document. (CVS 2647) check-in: 4c8d0a4c user: drh tags: trunk
Changes
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Changes to www/faq.tcl.

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#
# Run this script to generated a faq.html output file
#
set rcsid {$Id: faq.tcl,v 1.29 2005/06/16 19:48:40 drh Exp $}
source common.tcl
header {SQLite Frequently Asked Questions</title>}

set cnt 1
proc faq {question answer} {
  set ::faq($::cnt) [list [string trim $question] [string trim $answer]]
  incr ::cnt
................................................................................
      ** SQLITE_SCHEMA. In this case the loop will execute again.
      */
      rc = sqlite3_finalize(pStmt);
    } while( rc==SQLITE_SCHEMA );
    
  </pre></blockquote>
}




















# End of questions and answers.
#############

puts {<h2>Frequently Asked Questions</h2>}

# puts {<DL COMPACT>}



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#
# Run this script to generated a faq.html output file
#
set rcsid {$Id: faq.tcl,v 1.30 2005/08/31 02:46:21 drh Exp $}
source common.tcl
header {SQLite Frequently Asked Questions</title>}

set cnt 1
proc faq {question answer} {
  set ::faq($::cnt) [list [string trim $question] [string trim $answer]]
  incr ::cnt
................................................................................
      ** SQLITE_SCHEMA. In this case the loop will execute again.
      */
      rc = sqlite3_finalize(pStmt);
    } while( rc==SQLITE_SCHEMA );
    
  </pre></blockquote>
}

faq {Why does ROUND(9.95,1)  return 9.9 instead of 10.0?
     Shouldn't 9.95 round up?} {
  <p>SQLite uses binary arithmetic and in binary, there is no
  way to write 9.95 in a finite number of bits.  The closest to
  you can get to 9.95 in a 64-bit IEEE float (which is what
  SQLite uses) is 9.949999999999999289457264239899814128875732421875.
  So when you type "9.95", SQLite really understands the number to be
  the much longer value shown above.  And that value rounds down.</p>

  <p>This kind of problem comes up all the time when dealing with
  floating point binary numbers.  The general rule to remember is
  that most fractional numbers that have a finite representation in decimal
  do not have a finite representation in binary.  And so they are
  approximated using the closest binary number available.  That
  approximation is usually very close, but it will be slightly off
  and in some cases can cause your results to be a little different
  from what you might expect.</p>
}

# End of questions and answers.
#############

puts {<h2>Frequently Asked Questions</h2>}

# puts {<DL COMPACT>}