Ada Decimal Arithmethic and Representations

Among the application domains for which Ada is being used or is under consideration, is the traditional COBOL domain of business data processing. However, Ada's arithmetic type facility does not readily handle the exact decimal model needed for financial computation, leaving a major impediment to a successful transition to Ada for Information Systems applications. The ADAR project addresses this shortcoming by providing a set of packages that define and implement decimal support in Ada 83. The ADAR packages include support for decimal data with up to 18 digits of precision, arithmetic operations with programmer control over rounding versus truncation, conversions to and from common external representations, and formatted output of decimal values based on COBOL's "picture" clauses. The ADAR packages offer a portable interface via a set of unit specifications, and a portable (although not necessarily efficient) reference implementation.

ADAR provides two approaches to decimal arithmetic: one through a discriminated private type, where discriminants establish precision (the number of digits) and scale (the number of digits to the right of the decimal point); and another through generic packages, where the effect of precision and scale is established via generic instantiation. For details on the two approaches, refer to the accompanying report in the SUMMARY.TXT file. Users can employ either or both of the approaches in their programs.

The design and development of ADAR was conducted by Mr. Robert Eachus and Mr. David Emery from the MITRE Corporation, and by Dr. Benjamin Brosgol.

15 Jan 93   1.0   Brosgol et al   Initial release to ASSET
12 Nov 93   1.0   ASSET           Initial release to the PAL

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