big.nut

This is an Electric Imp Squirrel fork of big.js - A small, fast JavaScript library for arbitrary-precision decimal arithmetic.

The little sister to bignumber.js. See also decimal.js, and here for the difference between them.

Features

• Simple API
• Replicates the toExponential, toFixed and toPrecision methods of JavaScript's Number type
• Stores values in an accessible decimal floating point format
• No dependencies
• Comprehensive documentation and test set

Differences from Big.js

• There are no Class properties - currently everything is an instance property. This means that Big.DP isn't "sticky" like the Big.js library.
  • This decision needs to be reviewed. We also need to make sure things like cloning preserve properties correctly.

Load

Copy the big.class.nut file into your Electric Imp Agent.

Use

In all examples below, local, semicolons and toString calls are not shown. If a commented-out value is in quotes it means toString has been called on the preceding expression.

The library exports a single function: Big, the constructor of Big number instances. It accepts a value of type Number, String or Big number Object.

x = Big(123.4567)
y = Big('123456.7e-3')             
z = Big(x)
x.eq(y) && x.eq(z) && y.eq(z)      // true

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

0.3 - 0.1                          // 0.19999999999999998
x = Big(0.3)
x.minus(0.1)                       // "0.2"
x                                  // "0.3"

The methods that return a Big 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

Like JavaScript's Number type, there are toExponential, toFixed and toPrecision methods.

x = new Big(255.5)
x.toExponential(5)                 // "2.55500e+2"
x.toFixed(5)                       // "255.50000"
x.toPrecision(5)                   // "255.50"

The maximum number of decimal places and the rounding mode used to round the results of the div, sqrt and pow (with negative exponent) methods is determined by the value of the DP and RM properties of the Big number constructor.

The other methods always give the exact result.

(From v3.0.0, multiple Big number constructors can be created, see Change Log below.)

Big.DP = 10
Big.RM = 1

x = Big(2);
y = Big(3);
z = x.div(y)                       // "0.6666666667"
z.sqrt()                           // "0.8164965809"
z.pow(-3)                          // "3.3749999995"
z.times(z)                         // "0.44444444448888888889"
z.times(z).round(10)               // "0.4444444445"

The value of a Big number is stored in a decimal floating point format in terms of a coefficient, exponent and sign.

x = Big(-123.456);
x.c                                // [1,2,3,4,5,6]    coefficient (i.e. significand)
x.e                                // 2                exponent
x.s                                // -1               sign

For further information see the API reference from the doc folder.

Test

The test directory contains the test scripts for each Big number method.

The tests can be run inside the imp Agent.

Be warned - many of the tests must be ran manually because of agent memory limitations. In the future these tests may be converted to .json files so that the agent can HTTP GET them a chunk at a time.

Performance

Performance has not yet been tested. It does generally work though :)

Feedback

Feedback is welcome.

Bugs/comments/questions? Open an issue, or email

Licence

See LICENCE.

Change Log

####3.1.3

• Minor documentation updates.
• Initial Conversion to Squirrel.

####3.1.2

• README typo.

####3.1.1

• API documentation update, including FAQ additions.

####3.1.0

• Renamed and exposed TO_EXP_NEG and TO_EXP_POS as Big.E_NEG and Big.E_POS.

####3.0.2

• Remove .npmignore, use files field in package.json instead.

####3.0.1

• Added sub, add and mul aliases.
• Clean-up after lint.

####3.0.0

• 10/12/14 Added multiple constructor functionality.
• No breaking changes or other additions, but a major code reorganisation, so v3 seemed appropiate.

####2.5.2

• 1/11/14 Added bower.json.

####2.5.1

• 8/06/14 Amend README requires.

####2.5.0

• 26/01/14 Added toJSON method so serialization uses toString.

####2.4.1

• 17/10/13 Conform signed zero to IEEEE 754 (2008).

####2.4.0

• 19/09/13 Throw instances of Error.

####2.3.0

• 16/09/13 Added cmp method.

####2.2.0

• 11/07/13 Added 'round up' mode.

####2.1.0

• 26/06/13 Allow e.g. .1 and 2..

####2.0.0

• 12/05/13 Added abs method and replaced cmp with eq, gt, gte, lt, and lte methods.

####1.0.1

• Changed default value of MAX_DP to 1E6

####1.0.0

• 7/11/2012 Initial release