modulus of numbers > 2.2 billion

[snowjoke]

VBA seems to handle numbers greater than the maximum value for Long (2,147,483,647) OK, as I understand it by using the Decimal number type, which is a subtype of Variant.

If you go to Immediates and type

?3000000000 + 1

you get

 3000000001

But if you type

?3000000000 mod 2

or try to do the same in a program, you get an overflow error.

Is there any way to get the modulus of such a number?

 

[shg]

if int(dbl/2) = dbl/2 then
   ' dbl mod 2 = 0

 

[shg]

... (duplicate)

 

[snowjoke]

Thanks - was going to ask what if I don't just want to find if the mod is zero, but I've gone one better and written this which seems to work...

Function bigMod(a, b)
    bigMod = Round((a / b - Int(a / b)) * b)
End Function

?bigMod(3000000002,3)
 2

 

[shg]

Why would you want to round?

Function BigMod(a, b) As Double
    BigMod = a - Int(a / b) * b
End Function

 

[snowjoke]

You get things like 1.99999999234242 otherwise.

The built-in mod function uses Round as well.

 

[shg]

It uses Round because it operates on Longs, which are integers (small i). The worksheet MOD function operates on Doubles.

EDIT: More specifically, the Mod operator rounds its operands, not its results.

 

[snowjoke]

I tried your version and it doesn't seem to need the Round... yep your version loses less precision; I'll change my function to that! Thanks.