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Overview
| Comment: | 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(). |
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| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | floating-point-conversions |
| Files: | files | file ages | folders |
| SHA1: | fd7bd4a59361be41b10522abc212cf56fb5e35b4 |
| User & Date: | drh 2012-06-19 03:35:05 |
Context
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2012-06-19
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| 03:59 | Fix an incorrect testcase for the round() function. All tests are passing now, including new real->text->real round-trip tests. check-in: 963eb24f user: drh tags: floating-point-conversions | |
| 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 | |
Changes
Changes to src/printf.c.
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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 ){
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if( sqlite3IsNaN((double)realvalue) ){
bufpt = "NaN";
length = 3;
break;
}
if( realvalue>0.0 ){
LONGDOUBLE_TYPE scale = 1.0;
while( realvalue>=1e100*scale && exp<=350 ){ scale *= 1e100;exp+=100;}
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 ){
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Changes to test/atof1.test.
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# Tests of the sqlite3AtoF() function.
#
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.
#
................................................................................
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} {}
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# Tests of the sqlite3AtoF() function.
#
set testdir [file dirname $argv0]
source $testdir/tester.tcl
expr srand(1)
for {set i 1} {$i<20000} {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.
#
................................................................................
db eval "SELECT $xf+0.0 AS a, \$x AS b" {
puts [format "\n%.60e\n%.60e\n%.60e" $x $a $b]
}
}
set y
} {1}
# Verify that round-trip real->text->real conversions using the quote()
# function preserve the bits of the numeric value exactly.
#
do_test 1.$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} {}
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