I suggest to add the following capabilities in field calculations:
1) calculated fields are not allowed to be used in a formula to calculate another field. Like X= Y + Z where Y is also a calculated field.
2) The same calculated field to be used in its own formula. Suppose that I want to have X=X+Y.
3) Simple field calculations on character fields. Like X=Y, and X=Y + Z
4) Field calculations in Layout Designer, and Report Designer. Sometimes we need to show the sum, or difference of two fields in a layout, or report, but it is not necessary to add a field to database for this purpose.