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exact-math

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Readme

Description

How does exact-math work?

All numbers in JavaScript are stored as 64-bits Floating point numbers. JavaScript has difficulties with precise floating point values.

Code	Result
var result = 0.1 + 0.2;	0.30000000000000004
var result = 0.4 * 0.2	0.08000000000000002
var result = 0.45 - 0.15;	0.30000000000000004
var result = .82 / 10;	0.08199999999999999

What can I use exact-math for?

you can do simple multipication, division, subtraction and addition arithmetic calculations and get precise results.
you can use exact-math to compare two results in if() condition.
you can use exact-math results as output values displayed for the users. (prevent 0.30000000000000004$)

Where can I check how does exact-math work?

The calculation simulator with exact-math implementation:

https://devrafalko.github.io/exact-math
The program computes all possible combinations of calculations between minimal and maximal value entered.
Put min:1 max:5 step:0.1 number:2 select:multiplication as example
You can check the difference in computing between js regular arithmetic operations and exact-math arithmetic operations (the errors will be shown).

Browser Support

Chrome	Firefox	IE	Safari	Opera
yes	yes	yes	yes	yes

Methods

name	description	syntax	parameters description	return value
add	`exactMath.add()` adds values passed as arguments.	`exactMath.add(arg1,arg2,...)`	You can set any number, but at least two, arguments of `Number` type, separated by comma. Don't use arithmetic signs between arguments.	The result of addition operation.
sub	`exactMath.sub()` subtracts values passed as arguments (from left* to righ)*.	`exactMath.sub(arg1,arg2,...)`	You can set any number, but at least two, arguments of `Number` type, separated by comma. Don't use arithmetic signs between arguments.	The result of subtraction operation.
mul	`exactMath.mul()` multiplies values passed as arguments.	`exactMath.mul(arg1,arg2,...)`	You can set any number, but at least two, arguments of `Number` type, separated by comma. Don't use arithmetic signs between arguments.	The result of multiplication operation.
div	`exactMath.div()` divides values passed as arguments (from left* to righ)*.	`exactMath.div(arg1,arg2,...)`	You can set any number, but at least two, arguments of `Number` type, separated by comma. Don't use arithmetic signs between arguments.	The result of division operation.

Syntax

//exactMath is the global object from exact-math.js

var mul = exactMath.mul(.1, .2, .5, .7);  //0.007
var sub = exactMath.sub(10, 0.5, 2, 3);    //4.5

var arr = [.1, .2, .4, .05, 7];
var fun = function(i){return arr[i]};
var add = exactMath.add(arr[1], fun(2), 5.3);    //5.9

var a = exactMath.add(5, 3);
var b = exactMath.sub(9, 1);
var c = exactMath.mul(a, b, exactMath.div(10, 2));   //320

var d = 34e-5;
var e = .1254e+3;
var f = exactMath.mul(d, e);    //0.042636

Implementation

with NodeJS

npm install exact-math --save

var m = require('exact-math'); //get the module
var result = m.mul(.5,.3);

with Browser

1. Add exact-math.js to the HTML file.

<head>
  <script src="exact-math.js"></script>
</head>

Any outer libraries needed. It is a fully JavaScript project.

2. Use `exactMath` global Object from `exact-math.js`.

var m = exactMath;
var result = m.mul(.5,.3);

License

Released under the MIT license.

Copyright (c) 2017 Paweł Rafałko dev.rafalko@gmail.com

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

exact-math