DecimalSharp

Decimal in C#. Port of decimal.js. Public domain.

An arbitrary-precision Decimal type for C#.

Documentation

• Overview
• Installation
• Use
• System requirements
• Development and testing
• Contributors

Overview

The primary goal of this project is to produce a translation of decimal.js to C# which is as close as possible to the original implementation.

Features

• Integers and floats
• Simple but full-featured API
• Also handles hexadecimal, binary and octal values
• No dependencies
• Comprehensive documentation and test set

This library also adds the trigonometric functions, among others, and supports non-integer powers.

For a lighter version of this library without the trigonometric functions use DecimalSharp.Light

Installation

You can install DecimalSharp via NuGet:

package manager:

$ PM> Install-Package DecimalSharp

NET CLI:

$ dotnet add package DecimalSharp

or download source code.

Use

In the code examples below, semicolons and ToString calls are not shown.

A BigDecimal number is created from a primitive number, string, or other BigDecimal number.

x = new BigDecimal(123.4567)
y = new BigDecimal("123456.7e-3")
z = new BigDecimal(x)
x.Eq(y) && x.Eq(z) && y.Eq(z)          // true

If using values with more than a few digits, it is recommended to pass strings rather than numbers to avoid a potential loss of precision.

// Precision loss from using numeric literals with more than 15 significant digits.
new BigDecimal(1.0000000000000001)         // "1"
new BigDecimal(88259496234518.57)          // "88259496234518.56"
new BigDecimal(99999999999999999999)       // "100000000000000000000"

// Precision loss from using numeric literals outside the range of simple values.
new BigDecimal(2e+308)                     // "Infinity"
new BigDecimal(1e-324)                     // "0"

// Precision loss from the unexpected result of arithmetic with simple values.
new BigDecimal(0.7 + 0.1)                  // "0.7999999999999999"

Strings can contain underscores as separators to improve readability.

x = new BigDecimal("2_147_483_647")

String values in binary, hexadecimal or octal notation are also accepted if the appropriate prefix is included.

x = new BigDecimal("0xff.f")         // "255.9375"
y = new BigDecimal("0b10101100")     // "172"
z = x.Plus(y)                        // "427.9375"

z.ToBinary()                         // "0b110101011.1111"
z.ToBinary(13)                       // "0b1.101010111111p+8"

x = new BigDecimal("0b1.1111111111111111111111111111111111111111111111111111p+1023")
// "1.7976931348623157081e+308"

A BigDecimal number is immutable in the sense that it is not changed by its methods.

0.3 - 0.1                              // 0.19999999999999998
x = new BigDecimal(0.3)
x.Minus(0.1)                           // "0.2"
x                                      // "0.3"

The methods that return a BigDecimal number can be chained.

x.Div(y).Plus(z).Times(9).Minus("1.234567801234567e+8").Plus(976.54321).Div("2598.11772")
x.Sqrt().Div(y).Pow(3).Gt(y.Mod(z))    // true

Many method names have a shorter alias.

x.SquareRoot().DividedBy(y).ToPower(3).Equals(x.Sqrt().Div(y).Pow(3))     // true
x.ComparedTo(y.Modulo(z).Negated() === x.Cmp(y.Mod(z).Neg())              // true

And there are IsNaN and IsFinite methods, as NaN and Infinity are valid BigDecimal values.

x = new BigDecimal(double.NaN)                                 // "NaN"
y = new BigDecimal(double.PositiveInfinity)                    // "Infinity"
x.IsNaN() && !y.IsNaN() && !x.IsFinite() && !y.IsFinite()      // true

There are ToExponential, ToFixed and ToPrecision methods.

x = new BigDecimal(255.5)
x.ToExponential(5)                     // "2.55500e+2"
x.ToFixed(5)                           // "255.50000"
x.ToPrecision(5)                       // "255.50"

There is also a ToFraction method with an optional maximum denominator argument.

z = new BigDecimal(355)
pi = z.DividedBy(113)        // "3.1415929204"
pi.ToFraction()              // [ "7853982301", "2500000000" ]
pi.ToFraction(1000)          // [ "355', '113" ]

All calculations are rounded according to the number of significant digits and rounding mode specified by the precision and rounding properties of the BigDecimal constructor.

For advanced usage, multiple BigDecimal constructors can be created, each with their own independent configuration which applies to all BigDecimal numbers created from it.

// Set the precision and rounding
var bigDecimalFactory = new BigDecimalFactory(new BigDecimalConfig()
{
	Precision = 5,
	Rounding = RoundingMode.ROUND_HALF_UP
});

// Create another Decimal constructor, optionally passing in a configuration object
var bigDecimalFactory2 = new BigDecimalFactory(new BigDecimalConfig()
{
	Precision = 9,
	Rounding = RoundingMode.ROUND_DOWN
});

x = bigDecimalFactory.BigDecimal(5)
y = bigDecimalFactory2.BigDecimal(5)

x.Div(3)                           // "1.6667"
y.Div(3)                           // "1.66666666"

The value of a BigDecimal is stored in a floating point format in terms of its digits, exponent and sign, but these properties should be considered read-only.

x = new BigDecimal(-12345.67);
x.c                                    // [ 12345, 6700000 ]    digits (base 10000000)
x.e                                    // 4                     exponent
x.s                                    // -1                    sign

For further information see the API reference documentation.

System requirements

DecimalSharp supports:

• Net 6

Development and testing

Make sure to rebuild projects every time you change code for testing.

Testing

To run tests:

$ dotnet test

Contributors

XeroXP.