this is still a bug. COMBIN should *only*
return integers or error values.

I agree and had always assumed as much. This little exercise proves
otherwise.

=MOD((COMBIN(9,3)-84),1)

Returns 1.

Biff

"Harlan Grove" wrote in message
oups.com...
Biff wrote...
So you'd think that A5: =MOD(A4,1) should have a remainder. Or is that
the
fudge factor in effect?

There it is:

=MOD((A1-A2),1)

1.4210854715202E-14
...

I hadn't thought of that, but this is still a bug. COMBIN should *only*
return integers or error values. If both its arguments are numbers,
it'll truncate them to integers, e.g., COMBIN(7.2,2.9) returns the same
result as COMBIN(5,2). If its arguments are integers, then numerically
it can only return integers.

If its result would be beyond Excel's capacity, e.g., COMBIN(1030,515),
no problem having it return #NUM!. If its result would take more than
15 decimal digits, no problem that it'd be only approximately correct
to 15 decimal digits (and it'd also be an integer). But when it could
easily be represented in 15 or fewer decimal digits, there's no excuse
for it not to be an integer.

FWIW, the standard approach when N gets large enough that FACT(N)
exceeds 15 decimal digits is to use
EXP(GAMMALN(N+1)-GAMMALN(k+1)-GAMMALN(N-k+1)), but in the case of N=9
and k=3, this returns 84.0000000106965, while (COMBIN(9,3)-84) is
negative. Leaves me wondering how Microsoft is calculating this.