17 -> 0x10001 mantissa -1 -> 0xfffff exponent ( or however many bits the exponent is represented by exact
------------ Scott Doctor scott at scottdoctor.com On 10/23/2015 12:46 AM, Keith Medcalf wrote: > You are thinking (and typing) in base 10. Computers use this new-fangled > thing called binary -- base 2. > The "floating point" type is IEEE 754 double precision binary (base 2) > floating point. > > SQLite does not use decimal floating point (IEEE 854-1987) or General Decimal > Arithmetic > http://speleotrove.com/decimal/decarith.html > as specified by IBM and implemented in many non-lite SQL Engines. > > >> -----Original Message----- >> From: sqlite-users-bounces at mailinglists.sqlite.org [mailto:sqlite-users- >> bounces at mailinglists.sqlite.org] On Behalf Of Scott Doctor >> Sent: Friday, 23 October, 2015 01:31 >> To: General Discussion of SQLite Database >> Subject: Re: [sqlite] Simple Math Question >> >> Something sounds wrong with this floating point issue. His example >> consists of two digit numbers with simple addition. The number 1.7 would >> be represented by the value 17 and an exponent of -1, which is an exact >> number, same with his other numbers. His math operations should give >> exact results since the operations are simple addition. Since he is not >> doing any multiplication or division, there should not be any resolution >> issues. His results using his simple equations should give exact >> answers. So something is not handling the numbers properly if he is not >> getting exact results. If the claims about floating point results in >> sqlite are as stated in this thread of messages then floating point >> should be entirely avoided and eliminated from sqlite as this implies >> that floating point operations are improperly implemented rendering >> useless and incorrect results. >> >> ------------ >> Scott Doctor >> scott at scottdoctor.com >> >> On 10/23/2015 12:14 AM, Dominique Devienne wrote: >>> On Thu, Oct 22, 2015 at 11:55 PM, Igor Tandetnik <igor at tandetnik.org> >> wrote: >>>> On 10/22/2015 4:25 PM, Rousselot, Richard A wrote: >>>> >>>>> FWIW, MySQL and Oracle both return all yes for that query. >>>>> >>>> In MySQL, 9.2 is a literal of DECIMAL type, which is in fact >> represented >>>> as a finite decimal fraction. SQLite doesn't have such a type. You >> would >>>> likely observe similar results in MySQL if you write your constants >> like >>>> this: 9.2e0 (scientific notation makes them have FLOAT or DOUBLE type). >>>> >>> And oracle's NUMBER can be up to 20 bytes (21 unsigned), stores number >> is >>> base-100, i.e. each byte represents 2 base-10 digits. >>> http://www.orafaq.com/wiki/Number >>> >>> SQLite only uses IEEE double, which often cannot represent accurately >> even >>> small (as in text) numbers with a decimal point. You can use Oracle's >>> BINARY_DOUBLE to force it using an IEEE double. FWIW. --DD >>> _______________________________________________ >>> sqlite-users mailing list >>> sqlite-users at mailinglists.sqlite.org >>> http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users >>> >>> >> _______________________________________________ >> sqlite-users mailing list >> sqlite-users at mailinglists.sqlite.org >> http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users > > > _______________________________________________ > sqlite-users mailing list > sqlite-users at mailinglists.sqlite.org > http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users > >
