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Creating a rotating image gallery in Excel VBA

Some days ago, someone posted in my favourite german office forum a question how to create an image gallery with rotating images in Excel VBA. The images may rotate in a circular orbit when the user clicks on an image. “Image 1” should take the position of “Image 2”, “Image 2” the position of “Image 3” and so on. Following image shows a screenshot of the sample Excel file which you can download at the end of this article and includes also the VBA Code.

Excel VBA Animator

Twitter and Excel

19.04.2009 is a microblogging service. The allowed maximal message length is about
140 characters. Generally you send a message via your internet browser. Ok, you’ll find many specialized tools on the net; however our most used software is Microsoft Excel. This was the beginning of our Excel Add-In.

In this article we would like to explain the base techniques we used for sending messages to Twitter. You’ll find also a sample open source project file, which can be downloaded. The sample uses parts of our code from the Add-In. At the end of our article we’ll shortly present the Excel Add-In.

Karatsuba algorithm with Excel VBA

Someone posted in my favorite german office forum - Office-Lösung - a new game:
“Let's multiply, starting with 2, the result with itself and so on”.

Have you ever tried to multiply large numbers in Excel? Well, Excel uses a number precision of 15 digits, beyound the numbers are rounded. Thus, formulas are not suitable. Can VBA do the job? Yes, but only partially since the data types are restricted too. In addition, we have also to consider the computing time for multiplying large numbers.

If you search the Internet, you’ll quickly find some interesting procedures for multiplying large numbers. One of them is the “Karatsuba algorithm” which significantly reduces the multiplication of two n-digit numbers. The algorithm replaces some multplications by additions.