Spreadsheet

A spreadsheet is a Computer program able to handle worksheets . In the beginning intended for the automated financial data processing, the Logiciel S spreadsheves are now used to carry out varied tasks, management of simple databases to the production of Graphique S, while passing by various analyzes Statistique S.

Worksheet to the spreadsheet

A worksheet , or spreadsheet in English, is a table (or roasts) most of the time financial information. Mathematically, a worksheet is a matrix. The worksheets are traditionally used in Comptabilité, the data being presented in columns (Débit/Crédit, for example). Certain data result from calculations (subtractions, additions, multiplications) between various columns. The automation of these calculations, made possible by data processing in the last quarter of the 20th century, brought an appreciable profit of Productivité.

The computerized worksheets were invented by Pardo and Landau, which deposited the patent corresponding in 1970. The concept was reinvented thereafter per daN Brincklin. The legend wants that Bricklin had the idea of the spreadsheet while attending a course, at the university. The professor, after having drawn in the table a large computation chart, found an error there and had to erase and recompute most of the boxes, whereas this process could have been automated using a computer. This idea led to the creation of VisiCalc, the first spreadsheet. VisiCalc was the application which made definitively rock the data processing of the statute of leisure for some impassioned towards the professional world and the Killer app which ensured the success of the computer APPLE II on which it was available as of 1979.

Note: The spreadsheet is sometimes called electronic day-book in Quebec, term borrowed from the Québécois countable terminology. The word spreadsheet however is appropriate more to data processing.

Functionalities and use of the spreadsheves

The first computer programming languages were conceived so as to treat and to leave the data in the form of tables, often on a printer. The techniques of programming evolved/moved since, and the data can be represented more effectively in the memory of the computer, rather than sequentially on a sheet of paper. A software spreadsheet is conceived so as to carry out general calculations while being based on relations space, and either temporal, between the data.

The majority of the other calculation programmes use time indeed, i.e. the logical order of the instructions, like first principle of organization. A well defined entrance point causes the execution of the first instruction, then all the instructions follow after.

On the contrary, in a worksheet, a whole of cells is defined, as well as space logical relations between them. In the first spreadsheves, these relations were in two dimensions, represented by a grid. With the wire of time, new functionalities appeared, like the organization of independent sheets but being able to be connected logically one to the other, in an embryo of the third dimension. The most advanced spreadsheves propose operations like the rotation or the transposition of matrices of data; and can present the data files graphically.

The cells of a worksheet are the functional equivalents of the variables in a sequential program. The cells can contain formulas, i.e. a series of instructions which make it possible to calculate their value starting from other variables of the worksheet, or starting from external variables (as the date or the hour). The spreadsheves use the concepts of relative and absolute references, for example, in order to facilitate the edition and the comprehension of the formulas.

In general, the spreadsheves automatically update the values of the cells which depend on a parameter which varied. The first spreadsheves used simplistic strategies, like the update of the cells in a particular order; the more modern spreadsheves calculate only the minimum necessary thanks to the construction of a tree of dependence between the cells.

The majority of the concepts met in sequential programming are found in the world of the spreadsheves. For example, the course of indexed loops is represented by a treatment of a table of cells, and an infinite loop can be obtained by referring reciprocally two cells (cyclic tree of dependence). The majority of the spreadsheves accept this type of cyclic references, whose execution can be controlled by the user or the program itself.

The power of the spreadsheves derives certainly from the intuitive capacity of the human brain to represent objects in space and to apprehend complex relations between these objects. Many people find easier to rather carry out a complex calculation in a spreadsheet than in an adapted software, and this in spite of the obvious inadequacy between the tool and the objectives.

Some formulas

Excel and OpenOffice.org Calc allow the writing of formulas of computation including of the functions in the cells.

The functions are however dependant on the localization of the version of the software.

An example of formula (without function), which carries out the addition of the values contained in the cells A5 and B3:

  • =A5+B3

Examples of formulas using of the functions whose names vary according to the language used:

French-speaking localization

  • =SOMME (A1: B2) This formula will calculate the sum of all the numbers of A1 with B2.
  • =MOYENNE (A3: C6) This formula will make the average of the numbers of A3 with C6.

Anglophone localization

  • =SUM (A1: B2) This formula will calculate the sum of all the numbers of A1 with B2.
  • =AVERAGE (A3: C6) This formula will make the average of the numbers of A3 with C6.

Other concepts

  • the dynamic cross Table or pilot of data of Excel and OOo Calc make it possible to generate a synthesis of the table.
  • the Filtrage makes it possible not to post that the lines corresponding to certain criteria
  • the Tri makes it possible to change the order of a block of cells
  • the Consolidation makes it possible to amalgamate several tables made up of with more the one line and/or column of labels, and of quantified data by applying to it a function selected by the user (Somme, Nombre, Moyenne…). The new table is adapted according to the wording.

Software

Old

Currently used

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