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
