VBA Constants and Variables

**crayons** · 11-05-2010, 05:14 AM

Hello,

I am fairly experenced excel user but I am relatively new to VBA (only started using it a couple of weeks ago).

I am currently trying to build a engineering spreadsheet for the design of foundations. this requires alot of functions and calculations.

What i am looking to do is use the spreadsheet as an input and output area only and carry out all the calculations in VBA so i want to refer to the spreadsheet as little as possible in the code.

My Idea to do this was to create a module with all the input parameters for the calculations that are required which would pick the values of the parameters from the values entered into the spreadsheet cells, these parameters could then be used throughout the programme code without having to refer back to the spreadsheet again.

One way I this this was expressing each parameter as a funtion e.g

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This works but seems to stop the spreadsheet updating automatically.

Ive tried using varibale and constants but theu dont allow you to refer to the spreadsheet.

I hope someone can help, this has been annoying me for the last couple of days

Thanks
Ian

**royUK** · 11-05-2010, 05:19 AM

Why not use excel's inbuilt Functions as much as possible, that would be much more efficient than using VBA

**Andy Pope** · 11-05-2010, 05:24 AM

The function will only update if you add a line to tell excel the function is volatile.

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Note that using the Volatile approach can make the workbook slow if there a lots of calculations.

If your function includes an argument that is linked to a cell then it will update automatically.

Useful site for engineering related excel things
http://newtonexcelbach.wordpress.com/

**romperstomper** · 11-05-2010, 05:33 AM

Your post does not comply with Rule 8 of our Forum RULES. Cross-posting is when you post the same question in other forums on the web. You'll find people are disinclined to respond to cross-posts because they may be wasting their time solving a problem that has been solved elsewhere. We prefer that you not cross-post at all, but if you do (and it's unlikely to go unnoticed), you MUST provide a link (copy the url from the address bar in your browser)to the cross-post. Expect cross-posts without a link to be closed a message will be posted by the moderator explaining why. We are here to help so help us help you!

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**dougaj4** · 11-05-2010, 08:14 PM

Ian - I'm the author of the blog that Andy linked to.

If you have a look at some of my spreadsheets posted there you'll see that I make a lot of use of VBA User Defined Functions. I definitely disagree that using the built in functions is necessarily more efficient. Using VBA is often more efficient, and is also likely to be more flexible and more robust.

In your example I'm not sure why you would write that as a function, rather than just using:
dia = Range("dia").value
in the code.

I tend to use variant arrays for data input; e.g.

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Note that:

Checking that InputData is a range allows the function to be used as a UDF, or called from VBA.
"Range" is case sensitive.
.Value2 works quicker than .Value (it dumps some formatting information you don't need anyway)
You can assign a VBA array to the function return value (which must be a variant). This array can then be used in another VBA routine, or returned to the spreadsheet by entering as an array function.

Please ask if you need more details of anything.

Andy - thanks for your support for the blog!