VBA Query

[2016LM]

Hi, I have a simple piece of code that calculates the mass of a gas at a known pressure within a fixed volume (please see below). However, when I run said code, I get a 'Run-time error '6': Overflow' error. When I scroll the curser across the offending line (i.e. m(1) =...) the last bit in brackets (i.e. ...(R * T * Z)) shows up as '(R * T * Z) = <Overflow>'. After several hours of head scratching, I found that if I slightly changed the ordering to (R * Z * T) i.e. reverse the T and Z, the code works.

Public Const V = 20
Public Const atm = 1.013
Public Const Mwt = 28.01
Public Const R = 8314
Public Const T = 278
Sub Example()
Dim P(1 To 2), m(1 To 2) As Variant
P(1) = 0
Z = 0.9991
m(1) = (P(1) + atm) * (10 ^ 5) * V * Mwt / (R * T * Z)
ActiveCell.Value = m(1)
End Sub

I'm not the most proficient VBA user (so I'm guessing the reason is obvious), but I am at a complete loss as to why reversing the Z and T variables would make a difference.

Any help / assistance / enlightenment anyone could provide would be much appreciated.

Kind regards,

2016LM

 

[Fluff]

The problem is with the R*T portion, I suspect that VBA is trying to assign that as an integer, but is you do R*Z its probably assigned as Double (as Z is a decimal)
If you make this change it should work

Public Const R As Long = 8314

 

[2016LM]

Hi Fluff,

Ah, that makes sense. Code works fine now, thanks for taking the time to review and reply with the answer, I really appreciate it.

Kind regards,
2016Lm

 

[Fluff]

Glad to help & thanks for the feedback