configuration.md (5059B)
1 # Configuration 2 3 Math.js contains a number of configuration options. 4 These options can be applied on a created mathjs instance and changed afterwards. 5 6 ```js 7 import { create, all } from 'mathjs' 8 9 // create a mathjs instance with configuration 10 const config = { 11 epsilon: 1e-12, 12 matrix: 'Matrix', 13 number: 'number', 14 precision: 64, 15 predictable: false, 16 randomSeed: null 17 } 18 const math = create(all, config) 19 20 // read the applied configuration 21 console.log(math.config()) 22 23 // change the configuration 24 math.config({ 25 number: 'BigNumber' 26 }) 27 ``` 28 29 The following configuration options are available: 30 31 - `epsilon`. The minimum relative difference used to test equality between two 32 compared values. This value is used by all relational functions. 33 Default value is `1e-12`. 34 35 - `matrix`. The default type of matrix output for functions. 36 Available values are: `'Matrix'` (default) or `'Array'`. 37 Where possible, the type of matrix output from functions is determined from 38 the function input: An array as input will return an Array, a Matrix as input 39 will return a Matrix. In case of no matrix as input, the type of output is 40 determined by the option `matrix`. In case of mixed matrix 41 inputs, a matrix will be returned always. 42 43 - `number`. The type of numeric output for functions which cannot 44 determine the numeric type from the inputs. For most functions though, 45 the type of output is determined from the the input: 46 a number as input will return a number as output, 47 a BigNumber as input returns a BigNumber as output. 48 49 For example the functions `math.evaluate('2+3')`, `math.parse('2+3')`, 50 `math.range('1:10')`, and `math.unit('5cm')` use the `number` configuration 51 setting. But `math.sqrt(4)` will always return the number `2` 52 regardless of the `number` configuration, because the input is a number. 53 54 Available values are: `'number'` (default), `'BigNumber'`, or `'Fraction'`. 55 [BigNumbers](../datatypes/bignumbers.js) have higher precision than the default 56 numbers of JavaScript, and [`Fractions`](../datatypes/fractions.js) store 57 values in terms of a numerator and denominator. 58 59 - `precision`. The maximum number of significant digits for BigNumbers. 60 This setting only applies to BigNumbers, not to numbers. 61 Default value is `64`. 62 63 - `predictable`. Predictable output type of functions. When true, output type 64 depends only on the input types. When false (default), output type can vary 65 depending on input values. For example `math.sqrt(-4)` returns `complex('2i')` when 66 predictable is false, and returns `NaN` when true. 67 Predictable output can be needed when programmatically handling the result of 68 a calculation, but can be inconvenient for users when evaluating dynamic 69 equations. 70 71 - `randomSeed`. Set this option to seed pseudo random number generation, making it deterministic. The pseudo random number generator is reset with the seed provided each time this option is set. For example, setting it to `'a'` will cause `math.random()` to return `0.43449421599986604` upon the first call after setting the option every time. Set to `null` to seed the pseudo random number generator with a random seed. Default value is `null`. 72 73 74 ## Examples 75 76 This section shows a number of configuration examples. 77 78 ### node.js 79 80 ```js 81 import { create, all } from 'mathjs' 82 83 const config = { 84 matrix: 'Array' // Choose 'Matrix' (default) or 'Array' 85 } 86 const math = create(all, config) 87 88 // range will output an Array 89 math.range(0, 4) // Array [0, 1, 2, 3] 90 91 // change the configuration from Arrays to Matrices 92 math.config({ 93 matrix: 'Matrix' // Choose 'Matrix' (default) or 'Array' 94 }) 95 96 // range will output a Matrix 97 math.range(0, 4) // Matrix [0, 1, 2, 3] 98 99 // create an instance of math.js with BigNumber configuration 100 const bigmath = create(all, { 101 number: 'BigNumber', // Choose 'number' (default), 'BigNumber', or 'Fraction' 102 precision: 32 // 64 by default, only applicable for BigNumbers 103 }) 104 105 // parser will parse numbers as BigNumber now: 106 bigmath.evaluate('1 / 3') // BigNumber, 0.33333333333333333333333333333333 107 ``` 108 109 ### browser 110 111 112 ```html 113 <!DOCTYPE HTML> 114 <html> 115 <head> 116 <script src="math.js" type="text/javascript"></script> 117 </head> 118 <body> 119 <script type="text/javascript"> 120 // the default instance of math.js is available as 'math' 121 122 // range will output a Matrix 123 math.range(0, 4) // Matrix [0, 1, 2, 3] 124 125 // change the configuration of math from Matrices to Arrays 126 math.config({ 127 matrix: 'Array' // Choose 'Matrix' (default) or 'Array' 128 }) 129 130 // range will output an Array 131 math.range(0, 4) // Array [0, 1, 2, 3] 132 133 // create a new instance of math.js with bignumber configuration 134 const bigmath = math.create({ 135 number: 'BigNumber', // Choose 'number' (default), 'BigNumber', or 'Fraction' 136 precision: 32 // 64 by default, only applicable for BigNumbers 137 }) 138 139 // parser will parse numbers as BigNumber now: 140 bigmath.evaluate('1 / 3') // BigNumber, 0.33333333333333333333333333333333 141 </script> 142 </body> 143 </html> 144 ```