rows formated as number gives different results than rows formated as currency: formated as number -997,5 -640,36 992,58 997,5 640,36 -992,58 =SUM -1,13686837721616E-013 formated as currency: -$997,50 -$640,36 $992,58 $997,50 $640,36 -$992,58 =SUM $0,00
taken from here http://ask.libreoffice.org/en/question/32375/calc-sum-error-for-currency/
Created attachment 104976 [details] Calc - showing Sum error for numbers
That's normal because the currency format rounds the displayed value to 2 decimals. Calculations do not always result in exact numbers, there may be round-off errors because not all decimal numbers can be exactly represented as binary floating point values.
its a sum! there shouldn't be any rounding errors at all!
Created attachment 104979 [details] same numbers, formated the same, just reordered = different result
attached a better example. imo summing up numbers should give always the same result, not matter which order they are, also there should be no rounding/precision errors when summing up numbers which are in a small range.
Please get acquainted with the IEEE 754 floating point format before you try to tell someone that there should be no error. Or read http://support.microsoft.com/default.aspx?scid=kb;EN-US;78113 And yes, summing floating point values does depend on the order the values are encountered. This is not a bug, this is a limitation in computer hardware and software and the same in most spreadsheet implementations. One can implement magnitude sorted sums and other sorts of tricks to get around the problem to some degree.