Help with Mathematical Operations

The menu item Math operations allows you to create new fields using values from existing fields in the data object currently in use.

Example:

For example, if a data object provided wind speed information in the form of the pair of values nwind and ewind (north wind and east wind), you could define the wind speed as:


  wind_speed  := (nwind*nwind+ewind*ewind)^.5      ## Note that := is provided by the form

where the "^" operator means "raise to the power". In this case, we need the square root of the sum of the squares of each wind component.

When you have finished entering the formula (or formulas, using successive sets of boxes), click on the 'Go' button. The data will be displayed, with the new field name(s) and values added as new column(s) of data to the right of the existing table.

Rules:

complete at least one equation, starting with the first ("1") set of boxes.
only NEW variables or parameters are allowed on left-hand-side of equation
available operators are:
- cos
- sin
- exp
- ln
- log10
- int
- common arithmetic operators: +, -, *, /, ^
the assignment portion,":=", of the equation is provided for you

Last modified: January 8, 1999