The components of a formula
Formulae are made up of four different components:
- Symbols - a range of fixed elements such as mathematical symbols (+, -, etc) and comparators (<, =, etc). Other 'symbol' elements are variable dates, enumerated values and baseline references.
- Functions - a wide range of elements that extend the scope of formulae. For example, some functions perform text searches on character strings, which can be useful if you want to identify certain types of task; other functions convert one type of expression to another.
- Fields - the complete range of Asta Powerproject fields (Cost, Duration, Priority, etc) is available for use in formulae. Every formula contains at least one field.
- Objects - a range of project objects, for example calendars, progress periods and charts. You may want to include an object in a formula to compare the start date of a task to the report date of a specific progress period, for example.
Notes on using durations into formulae
Durations must always be contained within single quotation marks when they are included in formulae, for example '6ed'. It is possible to enter durations that mix working and elapsed time, for example '3w 2ed', into formulae.
When displaying durations that mix working and elapsed time in the spreadsheet, the number of seconds in the working time element is added to the number of seconds in the elapsed element, and the total number of seconds is used to define the duration that is actually displayed.
Notes on using dates in formulae
Dates must always be contained within single quotation marks when they are included in formulae, for example '25/12/10'.
While you can add times to dates - for example '25/12/10 10:45' - you do not have to. Dates that are entered without times are assumed to have a time of midnight (0:00).
Notes on using currency amounts in formulae
Currency amounts must always be contained within single quotation marks when they are included in formulae, for example '£25'.
Notes on using character strings in formulae
Character strings must always be contained within double quotation marks when they are included in formulae, for example "%".
Character strings perform two useful roles within formulae:
- Adding explanatory text to formulae results, such as a percentage sign after the result of a calculation.
- Referencing user-defined fields and comparing these against user-defined enumerator values.
Special characters such as tabs are not supported and are stripped out of character strings if they included in formulae.