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Mattias Andersson, Michael Andreen, Andreas Eliasson, Jonas Enlund, Tomas Forsman, Martin Frojdh, Henrik Jernevad, Therese Kastel, Karin Rohsman, Gustaf Sanders, & Anders Sudow


In this paper we will present Astec – an auxiliary spreadsheet tool for unit checking. Astec is built as an add-on to the open-source spreadsheet package Jeks.

The software will perform unit checking in spreadsheets that make use of formulas with physical dimensions. This helps end users to quickly detect formula errors that occur due to invalid use of units.

We introduce a mechanism that automatically converts unit factors into compound units as they are entered. Units are treated as in ordinary physics formulas by using a set of predefined conversion rules.

We show that unit conversions can in fact be modeled as a shortest path problem, and we show how compound units can be simplified into smaller entities.


Visualization of errors using Astec
Visualization of errors using Astec

By using Astec three different errors can occur:

  • Unit errors. Those will occur when units of different kinds are added or substracted with each other.
  • Conversion errors. All conversions between units must be defined in the conversion manager. This error occurs when a conversion is performed even though its conversion rule does not exist.
  • Propagation errors. This error happens when a reference to a cell that has generated an error is used within a formula.


2005, Chalmers University of Technology

Full article

Introducing units in spreadsheets