Category Archives: Calculation

Excel User Voice and Workbook Calculate

Excel User Voice At the recent Excel Global Summit the Excel team were keen to explain how they have started using Excel User Voice to ask for and prioritise product improvement suggestions. There are 2 important things to note … Continue reading

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Writing Efficient VBA UDFs (Part13): MaxMinFair Resource Allocation – an array UDF example

Last year we got to spend a great day at Microsoft Research in Cambridge (UK). one presentation was about storage strategies and featured (amongst other stuff) an interesting algorithm called MaxMinFair. The MaxMinFair algorithm You can read about it here … Continue reading

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Excel Circular References: Calculation, Detection, Control and Removal

Circular references in Excel are generally bad news: They are slow to calculate They can be hard to detect An intentional circular reference can mask an unintended circular reference, They do not always converge The Status Bar always shows calculate … Continue reading

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Excel ForceFullCalculation: Trading off Editing speed vs Calculation speed

A recent post at Stack Overflow reminded me that I have not posted about the pros and cons of Excel’s Workbook.ForceFullCalculation property. So what does Workbook.ForceFullCalculation do? The simple answer is that it switches off Excel’s smart recalculation algorithm, so … Continue reading

Posted in Calculation, Memory, Uncategorized, VBA | Tagged | 7 Comments

Timing Excel Formula Calculations

I have written a couple of posts previously about the methodology of timing Excel calculations: A Quantum of Time – measuring time accurately The XIPS Challenge – how fast does Excel calculate? But rather than focus exclusively on how to … Continue reading

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Stacking (Appending) Arrays/Ranges in Excel: Formulas versus Functions Shootout

This post is a follow up to my last post Using Constant Arrays and Expressions in Excel Formulas. I will explore how some of the general purpose array-handling functions in FastExcel SpeedTools Extras compare with formulas using native Excel functions. … Continue reading

Posted in arrays, Calculation, Lookups, Uncategorized, XLL | Tagged , , , , , , , | 4 Comments

Using Constant Arrays and Array Expressions in Excel Formulas

How Excel handles array expressions and constants in single-cell and multi-cell formulas is not well documented. So here is my attempt to shed some light on the subject. What are Constant Arrays? Constant arrays are Excel formula expressions that allow … Continue reading

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Calling XLAM/XLL/Automation UDFs from VBA: Evaluate, Run, or Reference?

I have this nagging feeling that I do not know the best way to call UDFs from VBA. So after a couple of days of research here is what I have found out so far. The Available Methods Application.ExecuteExcel4Macro This … Continue reading

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Timing the Ins and Outs of User Defined Functions: Multi-Cell array formulas can be slow

I was looking at some multi-cell array formula UDFs with John and Rich and could not understand why they seemed so much slower than I expected. Each UDF (written as C++ XLLs) read data from around 200 cells using around … Continue reading

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Getting Used Range in an XLL UDF: Multi-threading and COM

In two previous blog posts I discussed why handling whole-column references efficiently in VBA UDFs meant that you had to find the used range for the worksheet containing the whole-column reference. The posts also discussed how using a cache for … Continue reading

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