## Floating point arithmetic, again [Software]

Dear Helmut,

» OK, write in =0.5-0.4-0.1 and in =A1=0

»    1. What do you expect?

I expect to read 0. Regarding : I would naturally expect it to return TRUE. But on the other hand, typing =0=0.5-0.4-0.1 returns FALSE, and I would not necessarily expect a two-step calculation to yield a result that differs from a one-step calculation. By the way I checked: =0=5-4-1 returns TRUE, so it is not that Excel just compares 0 to 0.5 and ignores the subsequent signs and figures.

»    2. What do you get?

returns 0, as expected. Switching to scientific notation gives 0,00E+00. So it doesn't look like we have some hidden decimals there that don't show because of the default display.

returns TRUE. Indeed the result I would normally expect. But this means that typing the comparison and the calculation in one cell, or the calculation in one cell and the comparison in another, gives different results.

» Try in =16-8-4-2-2, in =(16-8-4-2-2), and in =A1=B1. I bet it “works” as expected, since these numbers can be converted to binary digits without error.

Yes. But it works also with =5-4-1, in =(5-4-1), and in =A1=B1. So it works with 5, which is not a power of 2 ?

Regards
Ohlbe  Ing. Helmut Schütz 