Problems with ABS() function

[Jon100]

Got a bit of a strange problem -
I have two cells each containing a different formula, but both of which result in an identical answer (checked to 30 d.p.). When I subtract one from the other the answer is (as expected) zero. However, when i take the absolute value of the difference, the value is NOT zero. The answer I get is 1.14E-13.

Its just a small value but enough to totally screw my s/sheet up as i'm just performing a logic check on the cell - does it equal 0?

Can anyone help me out here? A solution? or an explanation at to how the ABS() function works.

Thanks in advance

[Richard Buttrey]

I guess that the cells are simply formatted to 30 d.p rather than rounded to 30.

The reason is that the two cells, even at 30 d.p. are not exactly the same. There is an extremely small residual difference. The way round is to wrap the formulae with a ROUND() function.

e.g.

=ROUND(ABS(cell1)-ABS(cell2),30)

or round the cells themselves first. =ROUND(cell1,30)

HTH