On 3 Jul 2014 23:00, "Paul D Anderson via Digitalmars-d-announce" < email@example.com> wrote: > > A candidate implementation of decimal numbers (arbitrary-precision > floating-point numbers) is available for review at > https://github.com/andersonpd/eris/tree/master/eris/decimal. This is a > substantial rework of an earlier implementation which was located at > https://github.com/andersonpd/decimal. > > This is a D language implementation of the General Decimal Arithmetic > Specification (http://www.speleotrove.com/decimal/decarith.pdf), which is > compliant with IEEE-754 and other standards as noted in the specification. > > The current implementation is not complete; there are a lot of TODOs and NOTEs > scattered throughout the code, but all the arithmetic and miscellaneous > operations listed in the spec are working, along with decimal versions of most > of the functions and constants in std.math. I think it is far enough along for > effective review. > > Briefly, this software adds the capability of properly rounded > arbitrary-precision floating-point arithmetic to the D language. All arithmetic > operations are governed by a "context", which specifies the precision (number of > decimal digits) and rounding mode for the operations. This same functionality > exists in most modern computer languages (for example, java.math.BigDecimal). > Unlike Java, however, which uses function syntax for arithmetic ops > (add(BigDecimal, BigDecimal), etc.), in D the same arithmetic operators that > work for floats or doubles work for decimal numbers. (Of course!) > > In this implementation decimal numbers having different contexts are different > types. The types are specified using template parameters for the precision, > maximum exponent value and rounding mode. This means that > Decimal!(9,99,Rounding.HALF_EVEN) is a different type than > Decimal!(19,199,Rounding.HALF_DOWN). They are largely interoperable, however. > Different decimal types can be cast to and from each > other. > > There are three standard decimal structs which fit into 32-, 64- and 128-bits of > memory, with 7, 16 and 34 digit precision, respectively. These are used for > compact storage; they are converted to their corresponding decimal numbers for > calculation. They bear the same relation to decimal numbers as Walter's > half-float type does to floats. > (http://www.drdobbs.com/cpp/implementing-half-floats-in-d/240146674). > Implementation of these still needs a little work, and will be added to github > very shortly. > > Major TODO items: > > 1) The current underlying integer type uses my own big integer struct > (eris.integer.extended) rather than std.bigint. This was mainly due to problems > with constness and CTFE of BigInts. These problems have since been resolved, but > I didn't want to switch over to BigInts until everything was working for fear of > introducing new bugs. > > 2) Integration of Decimal32, Decimal64 and Decimal128 structs are not complete. > (See above.) > > 3) Conversion to and from floats, doubles and reals is currently working but it > is slow. (Conversion is through strings: double to string to decimal and vice > versa.) > > 4) Still incomplete implementations of some functions in decimal.math: expm1, > acosh, atanh, possibly others. > > 5) More unit tests (always!).
Nice job. I would also add: 6) Rename the file decimal.d to package.d, and module eris.decimal.decimal to eris.decimal