Dear NAG,

I have just bought a new laptop, running 64-bit Windows. For many years I have been using your Library in Excel and I want to continue using it in the same way, however I don't know which version I should use. My old machine had 32-bit Windows Vista.

Our response,

The short answer is that it is very likely that on your new 64-bit operating system you will still use the same 32-bit NAG Library. Which version of the NAG Library (32/64-bit) to use actually depends on bitness (being 32-bit or 64-bit) of your Microsoft Office, not the bitness of Microsoft Windows. If Microsoft Excel is a 32-bit application then you need to use a 32-bit NAG Library. 64-bit Excel will require 64-bit NAG Library. OK, but how do you know which Excel you have?

All pre-2010 Excel versions are 32-bit, so here the answer is simple - only the 32-bit NAG Library will work. If you have Excel 2010 then it is highly likely that it is a 32-bit version, because these days the default installation of Office 2010 on a 64-bit Windows is 32-bit. This helps maintain backward compatibility with solutions built using previous versions on Microsoft Office. In 64-bit VBA7 the user needs to update his Declare statements and update address pointers, i.e. the VBA code needs to be modified. Using 64-bit Excel is recommended only to those users who work with 2GB or more of data.

Here's an easy way to check which version you have.

1. Open an empty Excel 2010 spreadsheet.
2. Click on the File menu tab and select Help.
3. On the right hand side you'll see information about your version of Excel, including the version number and its bitness.

Having checked which version of Excel you have, you can now proceed to NAG's downloads page and pick the right implementation of the NAG Library. Once you have downloaded and installed it please contact NAG Support and ask for a licence key. Do visit the NAG and Excel page as well. Here you will find many downloadable example spreadsheets that demonstrate how to use the NAG Library in Excel.