Formed in 2009, the Archive Team (not to be confused with the archive.org Archive-It Team) is a rogue archivist collective dedicated to saving copies of rapidly dying or deleted websites for the sake of history and digital heritage. The group is 100% composed of volunteers and interested parties, and has expanded into a large amount of related projects for saving online and digital history.
Decimal Type for Phobos
This code is a work in progress for a new type Decimal that follows the
"General Decimal Arithmetic Specification" http://speleotrove.com/decimal/decarith.html
Example
import stdxdecimal;
void main()
{
auto d1 = decimal("1.23");
auto d2 = decimal("1.23E-4");
auto d3 = decimal("1.23E4");
assert(d1.toString() == "1.23");
assert(d2.toString() == "0.000123");
assert(d3.toString() == "12300");
auto d4 = d1 + d2;
assert(d4.toString() == "1.230123");
auto d5 = d3 - d1;
assert(d5.toString() == "12298.87");
auto d6 = decimal!(HighPrecision)("1.000000000000000000000000000000000000000000000000001");
auto d7 = decimal!(HighPrecision)("1E-51");
auto d8 = d6 + d7;
assert(d8.toString() == "1.000000000000000000000000000000000000000000000000002");
}Current Features
| Feature | Implemented |
|---|---|
| Construction from strings/string-like ranges | ✓ |
| Construction from number types | ✓ |
| To decimal string | ✓ |
| To scientific string | |
| To engineering string | |
| All rounding types | |
| Overflow/Underflow Behavior | |
| Subnormal Behavior | |
| Clamping Behavior | |
| Equals | ✓ |
| toHash | |
| Compare | ✓ |
| Addition | ✓ |
| Subtraction | ✓ |
| Multiply | ✓ |
| Divide | ✓ |
| Divide-Integer | |
| Modulo | |
| DivMod | |
opOpAssign +,-,*,/,^^ |
|
Unary +,-,++,-- |
✓ |
opCast int,real,bool |
✓ |
| abs | ✓ |
| ln | |
| log10 | |
| exp | |
| sqrt | |
| power | |
| reduce |
Current Performance
Run on a 15", 2015 Macbook Pro, (rounded to the nearest ms; test values purposely avoid rounding, which is the slowest part by far)
| Test | BigInt |
Decimal (P = 16) |
Decimal (P = 64) |
Python Decimal |
Python Decimal (64 Digits) |
|---|---|---|---|---|---|
| Addition (n = 5M) | 594 ms | 3,383 ms | 6,414 ms | 799 ms | 741 ms |
| Subtraction (n = 5M) | 494 ms | 3,092 ms | 6,028 ms | 800 ms | 830 ms |
| Multiplication (n = 5M) | 156 ms | 448 ms | 1,797 ms | 695 ms | 1541 ms |
| Division (n = 1M) | 207 ms | 5,261 ms | 18,283 ms | 215 ms | 416 ms |
Run It Yourself
D: ldc2 -O -release bench.d source/stdxdecimal/package.d && ./bench
Python:
import timeit
timeit.timeit("c = a + b", setup="from decimal import Decimal; a = Decimal(10000.12); b = Decimal(5000000); c = None", number=5000000)
timeit.timeit("c = a + b", setup="from decimal import Decimal; a = Decimal(1000000000000000000000000000000000000000000000000000000000000000); b = Decimal(5000000000000000000000000000000000000000000000000000000000000000); c = None", number=5000000)
timeit.timeit("c = a - b", setup="from decimal import Decimal; a = Decimal(10000.12); b = Decimal(5000000); c = None", number=5000000)
timeit.timeit("c = a - b", setup="from decimal import Decimal; a = Decimal('10000000000000000000000000000000000000000000000000000000000000.12'); b = Decimal('5000000000000000000000000000000000000000000000000000000000000000'); c = None", number=5000000)
timeit.timeit("c = a * b", setup="from decimal import Decimal; a = Decimal(10000.12); b = Decimal(5000000); c = None", number=5000000)
timeit.timeit("c = a * b", setup="from decimal import Decimal; a = Decimal('10000000000000000000000000000000000000000000000000000000000000.12'); b = Decimal('5000000000000000000000000000000000000000000000000000000000000000'); c = None", number=5000000)
timeit.timeit("c = a / b", setup="from decimal import Decimal; a = Decimal(10000.12); b = Decimal(5000000); c = None", number=1000000)
timeit.timeit("c = a / b", setup="from decimal import Decimal; a = Decimal('10000000000000000000000000000000000000000000000000000000000000.12'); b = Decimal('5000000000000000000000000000000000000000000000000000000000000000'); c = None", number=1000000)