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Overview
Comment:Improved accuracy on text-to-real and real-to-text conversions. Most conversions now round-trip correctly. Still need to fix some corner cases.
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Timelines: family | ancestors | descendants | both | floating-point-conversions
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SHA1: 8ecffca900cd6a8922001fd458a266ce8c83fb66
User & Date: drh 2012-06-19 03:11:25
Context
2012-06-19
03:35
Round-trip conversions of real->text->real are now lossless on x64 with GCC. Untested on other platforms so far. Still a corner-case problem with round(). check-in: fd7bd4a5 user: drh tags: floating-point-conversions
03:11
Improved accuracy on text-to-real and real-to-text conversions. Most conversions now round-trip correctly. Still need to fix some corner cases. check-in: 8ecffca9 user: drh tags: floating-point-conversions
00:45
Improved rounding accuracy on text-to-float conversions. check-in: 699b792c user: drh tags: trunk
Changes
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Changes to src/func.c. 

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** "NULL".  Otherwise, the argument is enclosed in single quotes with
** single-quote escapes.
*/
static void quoteFunc(sqlite3_context *context, int argc, sqlite3_value **argv){
  assert( argc==1 );
  UNUSED_PARAMETER(argc);
  switch( sqlite3_value_type(argv[0]) ){
    case SQLITE_INTEGER:











    case SQLITE_FLOAT: {
      sqlite3_result_value(context, argv[0]);
      break;
    }
    case SQLITE_BLOB: {
      char *zText = 0;
      char const *zBlob = sqlite3_value_blob(argv[0]);
      int nBlob = sqlite3_value_bytes(argv[0]);








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** "NULL".  Otherwise, the argument is enclosed in single quotes with
** single-quote escapes.
*/
static void quoteFunc(sqlite3_context *context, int argc, sqlite3_value **argv){
  assert( argc==1 );
  UNUSED_PARAMETER(argc);
  switch( sqlite3_value_type(argv[0]) ){
    case SQLITE_FLOAT: {
      double r1, r2;
      r1 = sqlite3_value_double(argv[0]);
      char zBuf[50];
      sqlite3_snprintf(sizeof(zBuf), zBuf, "%!.15g", r1);
      sqlite3AtoF(zBuf, &r2, 20, SQLITE_UTF8);
      if( r1!=r2 ){
        sqlite3_snprintf(sizeof(zBuf), zBuf, "%!.20e", r1);
      }
      sqlite3_result_text(context, zBuf, -1, SQLITE_TRANSIENT);
      break;
    }
    case SQLITE_INTEGER: {
      sqlite3_result_value(context, argv[0]);
      break;
    }
    case SQLITE_BLOB: {
      char *zText = 0;
      char const *zBlob = sqlite3_value_blob(argv[0]);
      int nBlob = sqlite3_value_bytes(argv[0]);

Changes to src/printf.c. 

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** The counter *cnt is incremented each time.  After counter exceeds
** 16 (the number of significant digits in a 64-bit float) '0' is
** always returned.
*/
static char et_getdigit(LONGDOUBLE_TYPE *val, int *cnt){
  int digit;
  LONGDOUBLE_TYPE d;
  if( (*cnt)++ >= 16 ) return '0';

  digit = (int)*val;
  d = digit;
  digit += '0';
  *val = (*val - d)*10.0;
  return (char)digit;
}
#endif /* SQLITE_OMIT_FLOATING_POINT */
................................................................................
        exp = 0;
        if( sqlite3IsNaN((double)realvalue) ){
          bufpt = "NaN";
          length = 3;
          break;
        }
        if( realvalue>0.0 ){
          while( realvalue>=1e32 && exp<=350 ){ realvalue *= 1e-32; exp+=32; }
          while( realvalue>=1e8 && exp<=350 ){ realvalue *= 1e-8; exp+=8; }
          while( realvalue>=10.0 && exp<=350 ){ realvalue *= 0.1; exp++; }


          while( realvalue<1e-8 ){ realvalue *= 1e8; exp-=8; }
          while( realvalue<1.0 ){ realvalue *= 10.0; exp--; }
          if( exp>350 ){
            if( prefix=='-' ){
              bufpt = "-Inf";
            }else if( prefix=='+' ){
              bufpt = "+Inf";
................................................................................
          if( exp<-4 || exp>precision ){
            xtype = etEXP;
          }else{
            precision = precision - exp;
            xtype = etFLOAT;
          }
        }else{
          flag_rtz = 0;
        }
        if( xtype==etEXP ){
          e2 = 0;
        }else{
          e2 = exp;
        }
        if( e2+precision+width > etBUFSIZE - 15 ){
................................................................................
          bufpt = zExtra = sqlite3Malloc( e2+precision+width+15 );
          if( bufpt==0 ){
            pAccum->mallocFailed = 1;
            return;
          }
        }
        zOut = bufpt;
        nsd = 0;
        flag_dp = (precision>0 ?1:0) | flag_alternateform | flag_altform2;
        /* The sign in front of the number */
        if( prefix ){
          *(bufpt++) = prefix;
        }
        /* Digits prior to the decimal point */
        if( e2<0 ){








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** The counter *cnt is incremented each time.  After counter exceeds
** 16 (the number of significant digits in a 64-bit float) '0' is
** always returned.
*/
static char et_getdigit(LONGDOUBLE_TYPE *val, int *cnt){
  int digit;
  LONGDOUBLE_TYPE d;
  if( (*cnt)<=0 ) return '0';
  (*cnt)--;
  digit = (int)*val;
  d = digit;
  digit += '0';
  *val = (*val - d)*10.0;
  return (char)digit;
}
#endif /* SQLITE_OMIT_FLOATING_POINT */
................................................................................
        exp = 0;
        if( sqlite3IsNaN((double)realvalue) ){
          bufpt = "NaN";
          length = 3;
          break;
        }
        if( realvalue>0.0 ){
          LONGDOUBLE_TYPE scale = 1.0;
          while( realvalue>=1e64*scale && exp<=350 ){ scale *= 1e64; exp+=64; }
          while( realvalue>=1e8*scale && exp<=350 ){ scale *= 1e8; exp+=8; }
          while( realvalue>=10.0*scale && exp<=350 ){ scale *= 10.0; exp++; }
          realvalue /= scale;
          while( realvalue<1e-8 ){ realvalue *= 1e8; exp-=8; }
          while( realvalue<1.0 ){ realvalue *= 10.0; exp--; }
          if( exp>350 ){
            if( prefix=='-' ){
              bufpt = "-Inf";
            }else if( prefix=='+' ){
              bufpt = "+Inf";
................................................................................
          if( exp<-4 || exp>precision ){
            xtype = etEXP;
          }else{
            precision = precision - exp;
            xtype = etFLOAT;
          }
        }else{
          flag_rtz = flag_altform2;
        }
        if( xtype==etEXP ){
          e2 = 0;
        }else{
          e2 = exp;
        }
        if( e2+precision+width > etBUFSIZE - 15 ){
................................................................................
          bufpt = zExtra = sqlite3Malloc( e2+precision+width+15 );
          if( bufpt==0 ){
            pAccum->mallocFailed = 1;
            return;
          }
        }
        zOut = bufpt;
        nsd = 16 + flag_altform2*10;
        flag_dp = (precision>0 ?1:0) | flag_alternateform | flag_altform2;
        /* The sign in front of the number */
        if( prefix ){
          *(bufpt++) = prefix;
        }
        /* Digits prior to the decimal point */
        if( e2<0 ){

Changes to test/atof1.test. 

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#

set testdir [file dirname $argv0]
source $testdir/tester.tcl

expr srand(1)
for {set i 1} {$i<10000} {incr i} {
  do_test 1.$i {
    set pow [expr {int((rand()-0.5)*100)}]
    set x [expr {pow((rand()-0.5)*2*rand(),$pow)}]
    set xf [format %.45e $x]





    set y [db eval "SELECT $xf=\$x"]
    if {!$y} {
      puts -nonewline \173[db eval "SELECT real2hex($xf), real2hex(\$x)"]\175
      db eval "SELECT $xf+0.0 AS a, \$x AS b" {
        puts [format "\n%.60e\n%.60e\n%.60e" $x $a $b]
      }
    }




















    set y
  } {1}
}


finish_test








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#

set testdir [file dirname $argv0]
source $testdir/tester.tcl

expr srand(1)
for {set i 1} {$i<10000} {incr i} {

  set pow [expr {int((rand()-0.5)*100)}]
  set x [expr {pow((rand()-0.5)*2*rand(),$pow)}]
  set xf [format %.32e $x]

  # Verify that text->real conversions get exactly same ieee754 floating-
  # point value in SQLite as they do in TCL.
  #
  do_test 1.$i.1 {
    set y [db eval "SELECT $xf=\$x"]
    if {!$y} {
      puts -nonewline \173[db eval "SELECT real2hex($xf), real2hex(\$x)"]\175
      db eval "SELECT $xf+0.0 AS a, \$x AS b" {
        puts [format "\n%.60e\n%.60e\n%.60e" $x $a $b]
      }
    }
    set y
  } {1}

  # FIX ME.  The following tests (real->text->real round-trips) sometimes
  # fail for large floating-point values.  Skip them for now...
  #
  if {abs($x)>1e50} continue

  # Verify that round-trip real->text->real conversions using the quote()
  # function preserve the bits of the numeric value exactly.
  #
  do_test 1.$i.2 {
    set y [db eval {SELECT $x=CAST(quote($x) AS real)}]
    if {!$y} {
      db eval {SELECT real2hex($x) a, real2hex(CAST(quote($x) AS real)) b} {}
      puts "\nIN:    $a $xf"
      puts [format {QUOTE: %16s %s} {} [db eval {SELECT quote($x)}]]
      db eval {SELECT CAST(quote($x) AS real) c} {}
      puts "OUT:   $b [format %.32e $c]"
    }
    set y
  } {1}
}


finish_test

Changes to test/date.test. 

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datetest 2.51 {datetime('2003-10-22 12:24','nonsense')} NULL

datetest 3.1 {strftime('%d','2003-10-31 12:34:56.432')} 31
datetest 3.2.1 {strftime('pre%fpost','2003-10-31 12:34:56.432')} pre56.432post
datetest 3.2.2 {strftime('%f','2003-10-31 12:34:59.9999999')} 59.999
datetest 3.3 {strftime('%H','2003-10-31 12:34:56.432')} 12
datetest 3.4 {strftime('%j','2003-10-31 12:34:56.432')} 304
datetest 3.5 {strftime('%J','2003-10-31 12:34:56.432')} 2452944.02426426
datetest 3.6 {strftime('%m','2003-10-31 12:34:56.432')} 10
datetest 3.7 {strftime('%M','2003-10-31 12:34:56.432')} 34
datetest 3.8.1 {strftime('%s','2003-10-31 12:34:56.432')} 1067603696
datetest 3.8.2 {strftime('%s','2038-01-19 03:14:07')} 2147483647
datetest 3.8.3 {strftime('%s','2038-01-19 03:14:08')} 2147483648
datetest 3.8.4 {strftime('%s','2201-04-09 12:00:00')} 7298164800
datetest 3.8.5 {strftime('%s','9999-12-31 23:59:59')} 253402300799








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datetest 2.51 {datetime('2003-10-22 12:24','nonsense')} NULL

datetest 3.1 {strftime('%d','2003-10-31 12:34:56.432')} 31
datetest 3.2.1 {strftime('pre%fpost','2003-10-31 12:34:56.432')} pre56.432post
datetest 3.2.2 {strftime('%f','2003-10-31 12:34:59.9999999')} 59.999
datetest 3.3 {strftime('%H','2003-10-31 12:34:56.432')} 12
datetest 3.4 {strftime('%j','2003-10-31 12:34:56.432')} 304
datetest 3.5 {strftime('%J','2003-10-31 12:34:56.432')} 2452944.024264259
datetest 3.6 {strftime('%m','2003-10-31 12:34:56.432')} 10
datetest 3.7 {strftime('%M','2003-10-31 12:34:56.432')} 34
datetest 3.8.1 {strftime('%s','2003-10-31 12:34:56.432')} 1067603696
datetest 3.8.2 {strftime('%s','2038-01-19 03:14:07')} 2147483647
datetest 3.8.3 {strftime('%s','2038-01-19 03:14:08')} 2147483648
datetest 3.8.4 {strftime('%s','2201-04-09 12:00:00')} 7298164800
datetest 3.8.5 {strftime('%s','9999-12-31 23:59:59')} 253402300799

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