> There seems to be a bug with the rounding function that means it's
> inconsistent in some circumstances. Below is some code to demonstrate it,
> but
> does anyone have any idea why the behaviour changes post compile?:
>
> Dim c1 As Currency
> Dim c2 As Currency
> Dim c3 As Currency
>
> c1 = 41.5
> c2 = 5
> c3 = c1 / 100 * c2
>
> MsgBox ("the following calculations should all return the same value based
> on bankers rounding" & _
>    ", but they differ between IDE debugging and running it compiled.")
> 'If you put these in as numbers directly the result is wrong consistently.
> MsgBox ("c1 is " & c1 & " and c2 is " & c2 & vbCrLf & _
>    "Round(c1 / 100 * c2, 2) returns: " & Round(c1 / 100 * c2, 2))
>
> MsgBox ("c3 is " & c3 & vbCrLf & _
>    "Round(c3, 2) returns: " & Round(c3, 2))
>
> 'If you put them in as variables then they're correct when you run
> 'in code through the IDE.
> 'However, when you run this as a compiled executable then you
> 'get the incorrect result again.
>
> MsgBox ("Round(2.075, 2) reutrns :" & Round(2.075, 2))

"Rick Rothstein (MVP - VB)" wrote:

> > There seems to be a bug with the rounding function that means it's
> > inconsistent in some circumstances. Below is some code to demonstrate it,
> > but
> > does anyone have any idea why the behaviour changes post compile?:
> >
> > Dim c1 As Currency
> > Dim c2 As Currency
> > Dim c3 As Currency
> >
> > c1 = 41.5
> > c2 = 5
> > c3 = c1 / 100 * c2
> >
> > MsgBox ("the following calculations should all return the same value based
> > on bankers rounding" & _
> >    ", but they differ between IDE debugging and running it compiled.")
> > 'If you put these in as numbers directly the result is wrong consistently.
> > MsgBox ("c1 is " & c1 & " and c2 is " & c2 & vbCrLf & _
> >    "Round(c1 / 100 * c2, 2) returns: " & Round(c1 / 100 * c2, 2))
> >
> > MsgBox ("c3 is " & c3 & vbCrLf & _
> >    "Round(c3, 2) returns: " & Round(c3, 2))
> >
> > 'If you put them in as variables then they're correct when you run
> > 'in code through the IDE.
> > 'However, when you run this as a compiled executable then you
> > 'get the incorrect result again.
> >
> > MsgBox ("Round(2.075, 2) reutrns :" & Round(2.075, 2))
>
> If you put the numbers into Currency variables first, then the calculations
> are carried out as integer calculations (Currency values are scaled integers
> which is why they have a fixed maximum number of decimal places; basically,
> the decimal point is eliminated, the integer calculation takes place and
> then the decimal point is reinserted)... integer calculation have no
> roundings when being carried out. However, when you use the numbers
> directly, the calculations take place as a floating point operation and is
> subject to all of the problems associated with them. These two links should
> give you a better insight into the floating point calculation problem...
>
> INFO: Visual Basic and Arithmetic Precision
> http://support.microsoft.com/default.aspx?scid=http://support.microsoft.com:80/support/kb/articles/Q279/7/55.ASP&NoWebContent=1
>
> (Complete) Tutorial to Understand IEEE Floating-Point Errors
> http://support.microsoft.com/default.aspx?scid=http://support.microsoft.com:80/support/kb/articles/Q42/9/80.ASP&NoWebContent=1
>
> Rick
>
>
>