We always store as strings to avoid rounding issues and then convert for calcs to whatever precision we need. Pat...
Sent from my iPhone > On Dec 17, 2014, at 6:24 AM, Lucio Chiappetti <lu...@lambrate.inaf.it> wrote: > >> On Tue, 16 Dec 2014, Hartmut Holzgraefe wrote: >>> On 16.12.2014 15:16, xiangdongzou wrote: >>> >>> Can anyone tell me why 531808.11 has been changed to 531808.12 ? >> >> typical decimal->binary->decimal conversion/rounding error. > > never used DECIMAL nor intend to, but the issue is typical of precision > issues among float (32-bit) and double (64-bit) in ANY programming language. > Google for "IEEE floating point" > > Some (most) users are unaware that a 32-bit real (REAL*4 for oldtimer Fortran > users like myself) have about 7 digits of precision, while 64-bit (doubles, > double precision, REAL*8) get to about 16. > > So if a quantity needs high precision (typically this occurs for angular > quantities where arcseconds are important), use double. > > -- > ------------------------------------------------------------------------ > Lucio Chiappetti - INAF/IASF - via Bassini 15 - I-20133 Milano (Italy) > For more info : http://www.iasf-milano.inaf.it/~lucio/personal.html > ------------------------------------------------------------------------ > Do not like Firefox >=29 ? Get Pale Moon ! http://www.palemoon.org > > -- > MySQL General Mailing List > For list archives: http://lists.mysql.com/mysql > To unsubscribe: http://lists.mysql.com/mysql > -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/mysql
