Encyclopedia
A
spreadsheet is a rectangular table of information, often
financial information. The word came from "spread" in its sense of a newspaper or magazine item that covers two facing pages, extending across the center fold and treating the two pages as one large one. The compound word "spread-sheet" came to mean the format used to present bookkeeping ledgers—with columns for categories of expenditures across the top, invoices listed down the left margin, and the amount of each payment in the cell where its row and column intersect—which were traditionally a "spread" across facing pages of a bound ledger or on oversized sheets of paper ruled into rows and columns in that format and approximately twice as wide as ordinary paper.
History
One of the first commercial uses of
computers was in processing payroll and other financial records, so the programs were designed to generate reports in the standard "spreadsheet" format bookkeepers and accountants used. As computers became more available and affordable in the last quarter of the 20th century, more
software became available for them, and programs to keep financial records and generate spreadsheet reports were always in demand. Those spreadsheet programs can be used to tabulate many kinds of information, not just financial records, so the term "spreadsheet" has developed a more general meaning as information presented in a rectangular table, usually generated by a computer.
The concept of an electronic spreadsheet was outlined in the 1961 paper "Budgeting Models and System Simulation" by Richard Mattessich. Some credit for the computerized spreadsheet perhaps belongs to Rene K. Pardo and Remy Landau, who filed on some of the related
algorithms in 1970. While the patent was initially rejected by the patent office as being a purely mathematical invention, Pardo and Landau won a court case in 1983 establishing that "something does not cease to become patentable merely because the point of novelty is in an algorithm." This case helped establish the viability of
software patents.
The generally recognized inventor of the spreadsheet as a commercial product for the
personal computer is Dan Bricklin although a fully interactive implementation produced in the
United Kingdom at
Imperial Chemical Industries running on an
IBM mainframe platform pre-dated his version by several years even featuring shared public spreadsheets from the outset.
Bricklin has spoken of watching his university professor create a table of calculation results on a blackboard. When the professor found an error, he had to tediously erase and rewrite a number of sequential entries in the table, triggering Bricklin to think that he could replicate the process on a computer, using the blackboard as the model to view results of underlying formulas. His idea became
VisiCalc, the first application that turned the
personal computer from a hobby for computer enthusiasts into a business tool.
VisiCalc went on to become the first "
killer app", an application that was so compelling, people would buy a particular computer just to own it. In this case the computer was the
Apple II, and VisiCalc was no small part in that machine's success. The program was later ported to a number of other early computers, notably
CP/M machines, the
Atari 8-bit family and various
Commodore platforms. Nevertheless, VisiCalc remains best known as "an Apple II program".
The acceptance of the
IBM PC following its introduction in August, 1981, began slowly, because most of the programs available for it were ports from other 8-bit platforms. Things changed dramatically with the introduction of
Lotus 1-2-3 in November, 1982, and release for sale in January, 1983. It became that platform's killer app, and drove sales of the PC due to the improvements in speed and graphics compared to VisiCalc. VisiCorp was unable to respond competitively, and disappeared within a few years.
Lotus 1-2-3 underwent an almost identical cycle with the introduction of
Windows 3.x in the late 1980s.
Microsoft had been developing
Excel on the
Macintosh platform for several years at this point, and it had developed into a fairly powerful system. A port to Windows 3.1 resulted in a fully-functional Windows spreadsheet which quickly took over from Lotus in the early 1990s. By the time Lotus responded with a usable Windows version of their own, Microsoft had started compiling their
Office suite, which still dominates the industry.
A number of companies have attempted to break into the spreadsheet market with programs based on very different paradigms. Lotus introduced what is likely the most successul example,
Lotus Improv, which saw some commercial success, notably in the financial world where its powerful data mining capabilities remain well respected to this day.
Spreadsheet 2000 attempted to dramatically simplify formula construction, but was generally not successful. Stories attempted to make it easier to deal with 3-D blocks of data , but appears to have seen little or no use.
Programming issues
Just as the early programming languages were designed to generate spreadsheet printouts, programming techniques themselves have evolved to process tables of data more efficiently in the computer itself.
Spreadsheets have evolved into powerful programming languages; specifically, they are functional, visual, and multiparadigm languages.
Many people find it easier to perform calculations in spreadsheets than by writing the equivalent sequential program. This is due to two traits of spreadsheets.
- They use spatial relationships to define program relationships. Like all animals, humans have highly developed intuitions about spaces, and of dependencies between items. Sequential programming usually requires typing line after line of text, which must be read slowly and carefully to be understood and changed.
- They are forgiving, allowing partial results and functions to work. One or more parts of a program can work correctly, even if other parts are unfinished or broken. This makes writing and debugging programs much easier, and faster. Sequential programming usually needs every program line and character to be correct for a program to run. One error usually stops the whole program and prevents any result.
A
spreadsheet program is designed to perform general computation tasks using spatial relationships rather than time as the primary organizing principle. Many programs designed to perform general computation use timing, the ordering of computational steps, as their primary way to organize a program. A well defined entry point is used to determine the first instructions, and all other instructions must be reachable from that point.
In a spreadsheet, however, a set of cells is defined, with a spatial relation to one another. In the earliest spreadsheets, these arrangements were a simple two-dimensional grid. Over time, the model has been expanded to include a third dimension, and in some cases a series of named grids. The most advanced examples allow inversion and rotation operations which can slice and project the data set in various ways.
The cells are functionally equivalent to variables in a sequential programming model. Cells often have a formula, a set of instructions which can be used to compute the value of a cell. Formulas can use the contents of other cells or external variables such as the current date and time. It is often convenient to think of a spreadsheet as a mathematical
graph, where the nodes are spreadsheet cells, and the edges are references to other cells specified in formulas. This is often called the dependency graph of the spreadsheet. References between cells can take advantage of spatial concepts such as relative position and absolute position, as well as named locations, to make the spreadsheet formulas easier to understand and manage.
Spreadsheets usually attempt to automatically update cells when the cells on which they depend have been changed. The earliest spreadsheets used simple tactics like evaluating cells in a particular order, but modern spreadsheets compute a minimal recomputation order from the dependency graph. Later spreadsheets also include a limited ability to propagate values in reverse, altering source values so that a particular answer is reached in a certain cell. Since spreadsheet cells formulas are not generally invertable, though, this technique is of somewhat limited value.
Many of the concepts common to sequential programming models have analogues in the spreadsheet world. For example, the sequential model of the
indexed loop is usually represented as a table of cells, with similar formulas.
Shortcomings
While extremely popular, spreadsheets are not without their downsides. Some of the problems associated with spreadsheets include,
- Lack of auditing and revision control. This makes it difficult to determine who changed what and when. This can cause problems with regulatory compliance, among other things.
- Lack of security. Generally, if one has permission to open a spreadsheet, one has permission to modify any part of it. This, combined with the lack of auditing above, can make easy for someone to commit fraud.
- Lack of concurrency. Unlike databases, spreadsheets typically allow only one user to be making changes at any given time.
- Because they are loosely structured, it is easy for someone to introduce an error, either accidentally or intentionally, by entering information in the wrong place or expressing dependencies among cells incorrectly.
While there are built-in and third-party tools for desktop spreadsheet applications that address some of these shortcomings, awareness of these is generally low, and usage lower still. However, many of these shortcomings can be handled by online spreadsheets like
Google Spreadsheets and
EditGrid.
Online spreadsheets
The advent of advanced
web technologies, such as Ajax and XUL, circa 2005 has propelled the emergence of a new generation of online spreadsheets. Equipped with a rich Internet application user experience, many of the online spreadsheets boast many of the features seen in desktop spreadsheet applications.
See also
- List of spreadsheets
- List of online spreadsheets
- Shared public spreadsheet
References
External links
General information
- by D.J. Power
-
- by Russell Schulz
-
- by Jocelyn Paine
- by Christopher Browne; much general information on spreadsheets, and some on related Linux issues
- , by Dan Bricklin
- on the Open Directory Project
- by Richard Mattessich
- - A classic video showing spreadsheet vendors going head-to-head in the late 80's .
Research organisations
