1 | // Convert from Fraction to BigNumber
|
2 | //
|
3 | // In the configuration of math.js one can specify the default number type to
|
4 | // be `number`, `BigNumber`, or `Fraction`. Not all functions support `Fraction`
|
5 | // or `BigNumber`, and if not supported these input types will be converted to
|
6 | // numbers.
|
7 | //
|
8 | // When `Fraction` is configured, one may want to fallback to `BigNumber`
|
9 | // instead of `number`. Also, one may want to be able to mix `Fraction` and
|
10 | // `BigNumber` in operations like summing them up. This can be achieved by
|
11 | // adding an extra conversion to the list of conversions as demonstrated in
|
12 | // this example.
|
13 |
|
14 | // Create an empty math.js instance, with only typed
|
15 | // (every instance contains `import` and `config` also out of the box)
|
16 | const { create, typedDependencies, all } = require('../..')
|
17 | const math = create({
|
18 | typedDependencies
|
19 | })
|
20 |
|
21 | // TODO: this should be much easier
|
22 | const allExceptLoaded = Object.keys(all)
|
23 | .map(key => all[key])
|
24 | .filter(factory => math[factory.fn] === undefined)
|
25 |
|
26 | // Configure to use fractions by default
|
27 | math.config({ number: 'Fraction' })
|
28 |
|
29 | // Add a conversion from Faction -> BigNumber
|
30 | // this conversion:
|
31 | // - must be inserted in the conversions list before the conversion Fraction -> number
|
32 | // - must be added to the conversions before loading functions into math.js
|
33 | math.typed.conversions.unshift({
|
34 | from: 'Fraction',
|
35 | to: 'BigNumber',
|
36 | convert: function (fraction) {
|
37 | return new math.BigNumber(fraction.n).div(fraction.d)
|
38 | }
|
39 | })
|
40 |
|
41 | // Import all data types, functions, constants, the expression parser, etc.
|
42 | math.import(allExceptLoaded)
|
43 |
|
44 | // Operators `add` and `divide` do have support for Fractions, so the result
|
45 | // will simply be a Fraction (default behavior of math.js).
|
46 | const ans1 = math.evaluate('1/3 + 1/4')
|
47 | console.log(math.typeOf(ans1), math.format(ans1))
|
48 | // outputs "Fraction 7/12"
|
49 |
|
50 | // Function sqrt doesn't have Fraction support, will now fall back to BigNumber
|
51 | // instead of number.
|
52 | const ans2 = math.evaluate('sqrt(4)')
|
53 | console.log(math.typeOf(ans2), math.format(ans2))
|
54 | // outputs "BigNumber 2"
|
55 |
|
56 | // We can now do operations with mixed Fractions and BigNumbers
|
57 | const ans3 = math.add(math.fraction(2, 5), math.bignumber(3))
|
58 | console.log(math.typeOf(ans3), math.format(ans3))
|
59 | // outputs "BigNumber 3.4"
|