Monthly Archives: October 2014

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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Automatic or Manual Calculation?: Grouped Sheets causes Calculation Confusion.

Thanks to Simon Hurst and Paul Wakefield for telling me about this calculation weirdo, and credit to Chatman at Accounting Web for discovering it. Grouped Sheets and Calculation Mode Try these experiments: Experiment 1 Start Excel Open a workbook in … Continue reading

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Excel 2007 multi-threading bug with Range.SubTotal and XLL

OK: this is a fairly obscure Excel 2007 only bug but I thought I should place it on record. The conditions required for the bug are: Excel 2007 (tested with 12.0.6683.5002 SP3) Automatic calculation Mode Multi-threaded calculation is on and … Continue reading

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