mathjs/examples/chaining.js

// chaining

// load math.js (using node.js)
const math = require('..')

// create a chained operation using the function `chain(value)`
// end a chain using done(). Let's calculate (3 + 4) * 2
const a = math.chain(3)
  .add(4)
  .multiply(2)
  .done()
print(a) // 14

// Another example, calculate square(sin(pi / 4))
const b = math.chain(math.pi)
  .divide(4)
  .sin()
  .square()
  .done()
print(b) // 0.5

// A chain has a few special methods: done, toString, valueOf, get, and set.
// these are demonstrated in the following examples

// toString will return a string representation of the chain's value
const chain = math.chain(2).divide(3)
const str = chain.toString()
print(str) // "0.6666666666666666"

// a chain has a function .valueOf(), which returns the value hold by the chain.
// This allows using it in regular operations. The function valueOf() acts the
// same as function done().
print(chain.valueOf()) // 0.66666666666667
print(chain + 2) // 2.6666666666667

// the function subset can be used to get or replace sub matrices
const array = [[1, 2], [3, 4]]
const v = math.chain(array)
  .subset(math.index(1, 0))
  .done()
print(v) // 3

const m = math.chain(array)
  .subset(math.index(0, 0), 8)
  .multiply(3)
  .done()
print(m) // [[24, 6], [9, 12]]

/**
 * Helper function to output a value in the console. Value will be formatted.
 * @param {*} value
 */
function print (value) {
  const precision = 14
  console.log(math.format(value, precision))
}