I have on my Excel 2000 workbook some complex calculations. According to
Help, Excel "recalculates those cells that are dependent on other cells that
contain values that have changed." However, when I change cells on which the
complex calculations do not depend (or even if I simply apply the format
paintbrush to keep grouped columns the same width) it takes half a minute,
the same as when it recalculates the whole workbook.

I have set the calculation to Automatic, so that the non-complex formulas
get recalculated when I change their precedent cells. Based on the
information in Help, however, I believe that Excel is supposed to calculate
dependents only of changed cells, even in Automatic.

How can I prevent recalculation of cells whose precedents are unchanged?