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Final clean-up of the idea of using Dekker double-precision floating

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computations to improve accuracy.

FossilOrigin-Name: 40285d631072b79aba39cc20d4b217bdf0069f29ac9902cb97dec28d3e4cde11
This commit is contained in:
drh 2023-07-03 11:39:38 +00:00
parent bc2b65832e
commit 841e596ad0
3 changed files with 19 additions and 10 deletions
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manifest
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@ -1,5 +1,5 @@
C Squeeze\sas\smany\sbits\sas\swe\scan\sout\sof\snormalization.
D 2023-07-03T10:35:29.478
C Final\sclean-up\sof\sthe\sidea\sof\susing\sDekker\sdouble-precision\sfloating\ncomputations\sto\simprove\saccuracy.
D 2023-07-03T11:39:38.542
F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@ -705,7 +705,7 @@ F src/trigger.c ad6ab9452715fa9a8075442e15196022275b414b9141b566af8cdb7a1605f2b0
F src/update.c 0aa36561167a7c40d01163238c297297962f31a15a8d742216b3c37cdf25f731
F src/upsert.c 5303dc6c518fa7d4b280ec65170f465c7a70b7ac2b22491598f6d0b4875b3145
F src/utf.c ee39565f0843775cc2c81135751ddd93eceb91a673ea2c57f61c76f288b041a0
F src/util.c 78be1d552e7038265bb944ef26c9ef94514bd061da19323a0321dde2874f0907
F src/util.c 44855f67ac96b546b77b6c2ad128d1e28a56c495038cdda3cae25b8407442f3c
F src/vacuum.c 604fcdaebe76f3497c855afcbf91b8fa5046b32de3045bab89cc008d68e40104
F src/vdbe.c 74282a947234513872a83b0bab1b8c644ece64b3e27b053ef17677c8ff9c81e0
F src/vdbe.h 41485521f68e9437fdb7ec4a90f9d86ab294e9bb8281e33b235915e29122cfc0
@ -2041,8 +2041,8 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
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R 8a559af6860b1623fc9d9f5fb9393b11
U drh
Z 91cee9d1957f1c63a4a3d422340e91a7
Z 48672189b786297b4026c7966b4eccaa
# Remove this line to create a well-formed Fossil manifest.

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@ -1 +1 @@
25d1ad6df1ed460c2cc9f32e8a5106e121ae502044f83abf431c1d5b3879eb56
40285d631072b79aba39cc20d4b217bdf0069f29ac9902cb97dec28d3e4cde11

15
src/util.c
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@ -999,8 +999,8 @@ void sqlite3FpDecode(FpDecode *p, double r, int iRound, int mxRound){
/* Multiply r by powers of ten until it lands somewhere in between
** 1.0e+19 and 1.0e+17.
*/
if( sizeof(long double)>8 && 0 ){
long double rr = r;
if( sizeof(LONGDOUBLE_TYPE)>8 ){
LONGDOUBLE_TYPE rr = r;
if( rr>=1.0e+19 ){
while( rr>=1.0e+119L ){ exp+=100; rr *= 1.0e-100L; }
while( rr>=1.0e+29L ){ exp+=10; rr *= 1.0e-10L; }
@ -1012,6 +1012,15 @@ void sqlite3FpDecode(FpDecode *p, double r, int iRound, int mxRound){
}
v = (u64)rr;
}else{
/* If high-precision floating point is not available using "long double",
** then use Dekker-style double-double computation to increase the
** precision.
**
** The error terms on constants like 1.0e+100 computed using the
** decimal extension, for example as follows:
**
** SELECT decimal_sci(decimal_sub('1.0e+100',decimal(1.0e+100)));
*/
double rr = 0.0;
if( r>1.84e+19 ){
while( r>1.84e+119 ){
@ -1029,7 +1038,7 @@ void sqlite3FpDecode(FpDecode *p, double r, int iRound, int mxRound){
}else{
while( r<1.84e-82 ){
exp -= 100;
mul2(r, rr, 1.0e+100, -1.5902891109759918046, &r, &rr);
mul2(r, rr, 1.0e+100, -1.5902891109759918046e+83, &r, &rr);
}
while( r<1.84e+08 ){
exp -= 10;