On Mon, 2009-03-02 at 07:57 +0800, bill lam wrote: > On Sun, 01 Mar 2009, Morten Welinder wrote: > > > After upgraded to 1.9.4. Diff the gnumeric file with the previous > > > 1.8.3 > > > > This is deliberate. We need to store enough decimals to ensure > > that the number we had will come back unchanged. The number > > This is incorrect. The number pairs have the same bit pattern using > ieee 754 standard so that they are equal.
The ieee 754 does _not_describe a single bit pattern for every number. You can't even decide whether a number is representable or not in ieee 754 unless you also specify whether you are using ieee 754 single, double, double extended,... > Merely adding more digits > does no increase the accuracy. Adding more digits in the stored number allows transfer of these files from one instance of gnumeric to another that uses a differnet size of ieee 754 floating point number. > There is an article by Kahn who is the > driving force behind the IEEE 754 standard, and he got the Turing > Award in 1989 for his work on numerical analysis. > > How Java's Floating-Point Hurts Everyone Everywhere > by W. Kahan and J. D. Darcy (March 1998) > > http://www.cs.berkeley.edu/~wkahan/JAVAhurt.pdf > > The last page "Accuracy < Precision" > > From what I can see in your message, previous versions did not > deliberately find the minimum digit representation of floating point > number within the limit of ieee 754 standard. Of course not. Especially since there is no such thing as a "minimum digit representation of floating point number within the limit of ieee 754 standard" unless you also specify the size of floating point number. Andreas > -- Andreas J. Guelzow <aguel...@pyrshep.ca> _______________________________________________ gnumeric-list mailing list gnumeric-list@gnome.org http://mail.gnome.org/mailman/listinfo/gnumeric-list
