There doesn't seem to be a Frac() function available in LibreOffice Basic, so I always have to use my own function (which is probably slower than a native one would be): Function Frac(Value As Double) As Double Frac=Value-Fix(Value) End Function For example, Frac(-12.3456789) ⇨ -0.3456789 I use Frac() all the time and I can't be the only one who need it, can I? Among other things it's nice for separating time from time+date, even if there are other ways to do that. FRAC() also seems to be missing as a cell function.
In calc you can use =MOD(3.4,1) I think there is no need to add a FRAC function and there is no function specified in openformula, so implementing it would create some problems The basic function part is solved with this patch: http://cgit.freedesktop.org/libreoffice/core/commit/?id=556a61a2f86fef1f828b8352fae7a4c4ed1fdd78 (the commit message is misleading: it only adds the Frac function to basic not to calc)
Oops… I didn't think of the MOD() function (REST() in my case), I guess I should have. Well, then there is no problem after all. Thanks!