On Fri, Sep 19, 2014 at 11:46 AM, TimeOfDay.nl <[email protected]> wrote:
> I am looking at my SQLite database in two ways: > > 1. from PHP, in my application, thru 'select * from table' statements and > the such > 2. from Adminer, as a database management tool > > When I look at a field that is type Real, and has the value of -41.29 as > the entered value, the results differ. > > - The PHP select gives me -41.29 > - Adminer gives me -41.289999999999999147 > > Why this difference? Does the php library do something to 'round' numbers > to so-many decimals? > See http://www.sqlite.org/faq.html#q16 The think to remember is that IEEE floating point numbers are approximations. They are designed to solve real world physic problems. And in the real world it is pysically impossible to tell -41.29 and -41.289999999999999147 apart. So you might as well think of them as the same number. A 64-bit IEEE floating point number variable cannot, in fact, contain exactly -41.29. The closest it can get is -41.28999999999999914734871708787977695465087890625. SQLite doesn't even try to get that close - promising only that floating point value are correct to 15 significant digits. -- D. Richard Hipp [email protected] _______________________________________________ sqlite-users mailing list [email protected] http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
