Next Generation Spreadsheets for Microsoft Excel
by Eero Hyvönen and Stefano de Pascale
VTT Information Technology released at CeBIT'96 in Hannover, Germany, a next generation interval spreadsheet system, Range Solver, implemented as an add-in extension to MS Excel. Based on the pioneering research at VTT, Range Solver is the first implementation of interval arithmetic and constraint satisfaction for a commercial spreadsheet program in the world (Applications of Interval Computations, Kluwer, New York, 1996).
In real world problems, data available for financial and technical planning, design, analysis and decision making is often imprecise in many ways. For example, dollar's exchange rate tomorrow cannot be known for sure, the diameter of a shaft or the resistance of an electronic component has a tolerance, data from a sensor may be missing, etc. In current spreadsheet systems only precise numbers can be used, even in the presence of uncertain data. Computed results cannot then correspond to the real life situation at hand.
Next generation interval spread-sheets for Microsoft Excel.Range Solver's innovation is to use interval arithmetic instead of ordinary arithmetic. Interval arithmetic generalizes ordinary arithmetic by using value ranges, intervals, in addition to precise numbers. For example, if next year's interest rate is estimated to be in range 5%-7%, then interval [5,7] can be used in arithmetic computations. Furthermore, the idea of interval constraint satisfaction makes it possible to the user to set formula value ranges (eg, the desired profit in a budget plan) in which case argument ranges (eg, needed turnover etc.) are automatically bounded.
Interval programming in C++
Range Solver is based on VTT's InC++ family of C++ libraries for extended interval arithmetic, global optimization and constraint satisfaction. These libraries make the latest developments in interval analysis available to the mainstream C++ programmer.
Free demo and WWW information service
Range Solver consists of over 40.000 lines of C++ and Visual Basic code, but runs fast enough to be used on modern micro computers using MS Excel 5.0 (Windows NT) or MS Excel 7.0 (Windows 95). A free demo together with more information of the system and its underlying technology can be found at: http://www.vtt.fi/tte/projects/interval/range-solver/
Please contact
Eero Hyvönen - VTT Information Technology
Tel: +358 0 4566043
E-mail: eero.hyvonen@vtt.fi
