mathjs handles the loss of precision

official website

官网：math.js | an extensive math library for JavaScript and Node.js

github：GitHub - josdejong/mathjs: An extensive math library for JavaScript and Node.js

npm address: mathjs-npm

mathjs features:

• Numbers, large numbers, complex numbers, fractions, units, strings, arrays, and matrices are supported.
• Compatible with JavaScript's built-in math library.
• Contains a flexible expression parser.
• Perform symbolic calculations.
• Comes with a large number of built-in functions and constants.
• Can also be used as a command line application.
• Runs on any JavaScript engine.
• Easy to expand.
• open source.

Math.js is available in node.js and the browser.

Install math.js using npm :

npm install mathjs

Or download mathjs via one of the CDNs listed on the download page:

   <script src="https://cdn.bootcdn.net/ajax/libs/mathjs/10.6.1/math.min.js"></script>

How to use mathjs

The method of mathjs to obtain the operation value

1. valueof()
2. done()
3. format()
4. ...

Use static functions and constants (like JavaScript's Math object)

math.round(math.e, 3);            // 2.718
math.add(2, 3);  // 5 
math.sqrt(-4);  // 2i 
math.pow([[-1, 2], [3, 1]],2);     // [[7, 0], [0, 7]]
math.derivative('x^2 + x', 'x');  // 2 * x + 1
math.atan2(3, -3) / math.pi;      // 0.75

mathjs large numbers

If bignumber is not used, the calculation result will have precision problems

math.bignumber('2.3e+500') // BigNumber, 2.3e+500
print(math.add(0.1, 0.2)) // number, 0.30000000000000004
print(math.multiply(10.22, 100)). //1022.0000000000001
print(math.divide(0.3, 0.2)) // number, 1.4999999999999998

The first:

You can use the following function to create BigNumber to solve the precision problem of js calculation

print(math.add(math.bignumber(0.1), math.bignumber(0.2))) // BigNumber, 0.3
print(math.divide(math.bignumber(0.3), math.bignumber(0.2))) // BigNumber, 1.5

The second type:

Most functions can determine the type of output based on the type of input: a number as input will return a number as output, a BigNumber as input will return a BigNumber as output. Functions that cannot determine input and output types (for example math.evaluate) use default numeric types number, which can be configured when instantiating math.js. To configure to use BigNumbers instead of numbers by default, configure math.js like this:

const { create, all } = require('..')

// configure the default type of numbers as BigNumbers
const config = {
  number: 'BigNumber',
  precision: 64, 
}
const math = create(all, config)



math.evaluate('0.1 + 0.2')  // BigNumber, 0.3

 BigNumber has a default precision of 64 bits, which can be configured using the option

Addition, subtraction, multiplication and division

Example using bignumber:

​math.add(math.bignumber(0.1), math.bignumber(0.2)) // 加法 BigNumber, 0.3
math.subtract(math.bignumber(1), math.bignumber(0.9)) // 减法 BigNumber, 0.1
math.multiply(math.bignumber(4.10), math.bignumber(100)) // 乘法 BigNumber, 410
math.multiply(math.bignumber(10.22), math.bignumber(100)) //乘法 10.22
math.ceil(math.bignumber(6.10)/ math.bignumber(0.1));   //除法 向上取整 61
math.floor(math.bignumber(6.10)/ math.bignumber(0.1));   //除法 向下取整 61
math.round(math.bignumber(6.10)/ math.bignumber(0.1));   // 除法 四舍五入 61