Category Archives: arrays

Short-circuiting in Array Formulas

Posted on January 6, 2023 by fastexcel

The previous post demonstrated that IF and CHOOSE short-circuit but IFS and SWITCH do not. But following up a hint from Bill Wu that IF behaves differently in array formulas I decided to check whether it still short-circuits.(IF in array … Continue reading →

Posted in arrays, Calculation, Dynamic Arrays, Excel, UDF | Tagged | 5 Comments

FastExcel Version 4 – with Introductory Offer

Posted on February 5, 2020 by fastexcel

After several man-years of development and a lot of beta testing FastExcel Version 4 has finally hit general availability! FastExcel V4 is a major rewrite of FastExcel V3 and provides many of the things you have been asking for: Support … Continue reading →

Posted in arrays, Calculation, Debug formulas, Dynamic Arrays, Excel, Lookups, Memory, UDF, VBA | Leave a comment

Backward Compatibility of Office 365 Dynamic Arrays (Updated 23 Sep 2020)

Posted on May 20, 2019 by fastexcel

Office 365 Excel Dynamic Arrays are great, but: What happens when you create a workbook with Dynamic Array  Excel (Excel DA) and send it to someone who does not have Excel DA, and how do you write VBA code that … Continue reading →

Posted in arrays, Dynamic Arrays, Excel, Uncategorized, VBA | Tagged | 21 Comments

Develop Excel Conference

Posted on July 30, 2018 by fastexcel

The Develop Excel conference will take place in London on Thursday October the 18th 2018. It will be held at the Microsoft Reactor (70 Wilson Street London EC2A 2DB). Are you responsible for building Excel based Addins and Solutions? Develop … Continue reading →

Posted in .NET, arrays, Excel, JS-API, UDF, VBA, XLL | 2 Comments

Excel JavaScript API Part 4: The shallow copy problem

Posted on April 5, 2017 by fastexcel

I was trying to read the values from a Range and then write modified versions of the values to two different ranges. Should be straightforward: Well this does not work: both B4 and B6 have 0.91 added to them: wrong … Continue reading →

Posted in arrays, Excel, JS-API | Tagged , | 1 Comment

Excel JavaScript API Part 3: Benchmark of Processing Arrays Performance – Loop vs Reduce vs COUNTIFS vs VBA

Posted on March 16, 2017 by fastexcel

In a previous post I compared several different ways of processing data with VBA. The fastest way was to get the data into a variant array and loop on it. JavaScript has some powerful array methods so I wanted to … Continue reading →

Posted in arrays, JS-API, VBA | Tagged , , | 5 Comments

Excel JavaScript API Part 2: Benchmark of Read/Write Range Performance

Posted on March 13, 2017 by fastexcel

As an Excel Office Developer many of the Excel based applications I develop depend on reading data from Excel worksheet ranges, processing it and then writing the processed data back to a worksheet. In VBA the way to do this … Continue reading →

Posted in arrays, Calculation, JS-API, VBA | Tagged , , | 3 Comments

Writing Efficient VBA UDFs Part 14: Handling whole columns using Implicit Intersection – Updated

Posted on October 3, 2016 by fastexcel

Excel has an interesting and very efficient trick called Implicit Intersection which allows you to use large Named Ranges and whole column references efficiently. What is Implicit Intersection? When Excel expects to get a single cell reference but you give … Continue reading →

Posted in arrays, Calculation, UDF, VBA, XLL | Tagged , , , , | 15 Comments

Excel What-If Data Tables: Faster calculation with VBA

Posted on December 16, 2015 by fastexcel

For some reason this year I keep on meeting Excel’s What-If Data Tables. These are used (often in real estate and financial valuation models) to simplify doing sensitivity analysis against a range of values for certain inputs such as interest … Continue reading →

Posted in arrays, Calculation, VBA | 7 Comments

Excel Full Column References and Used Range: Good Idea or Bad Idea?

Posted on December 12, 2015 by fastexcel

Some people love using full column references such as A:A, other people say they slow down your workbook to a crawl and lead to workbook and memory bloat. The attraction of using whole column references is that you don’t have … Continue reading →

Posted in arrays, Calculation, Formatting, Memory | 5 Comments