Calculating Form Fields
You can create calculated fields on a form. To do this, you only need to specify a calculation method for the given field. If you do this, the field value is automatically calculated when displaying the form. If the field is dependent on the value of one or more other fields, you can set which other fields in the form should automatically recalculate their value if they change. If the calculated field does not need to be recalculated when a form item changes, the form allows you to recalculate all the fields.
Setting a calculation method for the a form item field (adding up the values of column1 and column2):
Sets if the calculatedItem should recalculate the field value if column1 or column2 changes:
Recalculating all form fields from code: