This application is a spreadsheet: Each file is a matrix of cells, and each cell can contain either data in some format, or a formula which relies on the values of other cells. To analyze data, the program supports different kinds of graphs, goal-finding algorithms and scripting.
|
The system shall support editing multiple spreadsheets in a multiple window user interface. A spreadsheet document is a matrix of cells, identified by a letter (column number) and number (row number). |
|
The system shall support these data types in cells: Integers, real numbers, strings, dates and formulas. A formula is a computed expression whose value depends on other cells, either in the current or other spreadsheet files. Defining a circle of dependencies is illegal, and should be caught and reported to the user. |
|
Formulas can include arithmetic operators, functions on numbers, strings and dates, and calling scripts that return values (see below). Errors in formulas (division by zero, illegal cell reference, unknown function, etc.) are caught while typing the formula, and the user will not be allowed to finish editing the cell before correcting the error. |
|
The system shall support immediate refresh of computed cells. When the user edits a cell, all cells whose value depend on it automatically update. If an error occurred during the computation (for example, a division by zero), all dependent cells must be marked with a special error display as well. The refresh must be efficient: only computation required to display the cells on the screen is allowed. |
|
The system shall support each cell having a font, color, size and display format. The display format of a cell determines whether it is shown as a formula or the value of the formula, a fixed real number or a currency, and so forth. |
|
The system shall support the copy, paste, find, and conditional fill/format (changing all cells that satisfy some value) operations, on any or all of the formula, value or the display settings of a dynamically defined set of cells. For example, a user can request to add 5% to all selected cells that contain a non-negative value and are displayed in bold. |
|
The system shall include a goal-finding feature. Such an algorithm tries to find what should the value of a given input cell be so that the value of another given cell will reach a desired value. For example, a user can compute what should the interest rate be so that s/he will have an annual profit of 1$ million. The goal finding feature need only work on numbers, but it should be easy to change its algorithm or extend it in the future. |
|
That system shall enable writing scripts, either ones that return a value (and can be used as functions in formulas), or ones that perform an action (and can be used in the program's menus). A script is a list of actions that may define variables, call API functions or other scripts, and support "if", "for" and "while" constructs. |
|
The system shall support plotting a dynamically selected set of cells as a chart (that opens as a new screen on the window). If a chart is on the screen, then it must immediately update when the data it depends on updates. Many types of charts are supported; the user can also program new chart types by writing a script that calls the "Chart API". |
|
The system shall support fast and efficient undo and redo of any command, at a depth limited only by the computer's memory. |
Each of these ten requirements are worth 10% of the grade on the exercise. Note that the grade of a single requirement is composed of how you dealt with it everywhere - in requirements, design, strong and weak spots, and the oral questions.
Good luck!