When I convert data from a spreadsheet into GEMPACK the numbers change, or become unbalanced. Why?
When you save a spreadsheet as a CSV (comma-separated values) file to convert the data to GEMPACK,
what you see is what you get.
This means that, if you have chosen to display numbers in the spreadsheet with only one decimal place, only one decimal place will go into the
CSV file (even though there may be more accuracy available in the spreadsheet).
To avoid this problem, you must change the display in the spreadsheet to show all the accuracy before you save the CSV file.
Even if you get 1 above right, the GEMPACK programs may appear to have less precision that was in the spreadsheet. This is because GEMPACK
programs only carry 7 or 8 significant figures. [In technical jargon, they always work in single precision.]
If, for example, your spreadsheet has large dollar amounts with more than 8 figures, these will be rounded to 7 or 8 figures in the GEMPACK
programs and data files. For example, 123456789.1 will be rounded to something like 123456790.
You can be confident that this rounding does not cause loss of accuracy with simulation results.
Because of the rounding done by GEMPACK programs, the balance of the data might seem to be not as accurate once you convert to GEMPACK. For
example, suppose that in some matrix the column sums should equal the row sums. This may happen to 9 figures in the spreadsheet but you may notice
differences after 7 figures (or even 6 if the matrix has 100 or so rows/columns) in the GEMPACK (or ViewHAR) totals.
This kind of rounding is inevitable whenever you do lots of arithmetic on a computer.
Again, you can be confident that this rounding does not cause loss of accuracy with simulation results.