Using the Default Precision Rules

Using the default precision rule, the precision of a decimal intermediate in an expression is computed to minimize the possibility of numeric overflow. However, if the expression involves several operations on large decimal numbers, the intermediates may end up with zero decimal positions. (Especially, if the expression has two or more nested divisions.) This may not be what the programmer expects, especially in an assignment.

When determining the precision of a decimal intermediate, two steps occur:

1. The desired or "natural" precision of the result is computed.
2. If the natural precision is greater than 63 digits, the precision is adjusted to fit in 63 digits. This normally involves first reducing the number of decimal positions, and then if necessary, reducing the total number of digits of the intermediate.

This behaviour is the default and can be specified for an entire module (using control specification keyword EXPROPTS(*MAXDIGITS) or for single free-form expressions (using operation code extender M).