102 lines
2.8 KiB
JavaScript
102 lines
2.8 KiB
JavaScript
// matrices
|
|
|
|
// load math.js (using node.js)
|
|
const math = require('..')
|
|
|
|
// create matrices and arrays. a matrix is just a wrapper around an Array,
|
|
// providing some handy utilities.
|
|
console.log('create a matrix')
|
|
const a = math.matrix([1, 4, 9, 16, 25])
|
|
print(a) // [1, 4, 9, 16, 25]
|
|
const b = math.matrix(math.ones([2, 3]))
|
|
print(b) // [[1, 1, 1], [1, 1, 1]]
|
|
print(b.size()) // [2, 3]
|
|
|
|
// the Array data of a Matrix can be retrieved using valueOf()
|
|
const array = a.valueOf()
|
|
print(array) // [1, 4, 9, 16, 25]
|
|
|
|
// Matrices can be cloned
|
|
const clone = a.clone()
|
|
print(clone) // [1, 4, 9, 16, 25]
|
|
console.log()
|
|
|
|
// perform operations with matrices
|
|
console.log('perform operations')
|
|
print(math.sqrt(a)) // [1, 2, 3, 4, 5]
|
|
const c = [1, 2, 3, 4, 5]
|
|
print(math.factorial(c)) // [1, 2, 6, 24, 120]
|
|
console.log()
|
|
|
|
// create and manipulate matrices. Arrays and Matrices can be used mixed.
|
|
console.log('manipulate matrices')
|
|
const d = [[1, 2], [3, 4]]
|
|
print(d) // [[1, 2], [3, 4]]
|
|
const e = math.matrix([[5, 6], [1, 1]])
|
|
print(e) // [[5, 6], [1, 1]]
|
|
|
|
// set a submatrix.
|
|
// Matrix indexes are zero-based.
|
|
e.subset(math.index(1, [0, 1]), [[7, 8]])
|
|
print(e) // [[5, 6], [7, 8]]
|
|
const f = math.multiply(d, e)
|
|
print(f) // [[19, 22], [43, 50]]
|
|
const g = f.subset(math.index(1, 0))
|
|
print(g) // 43
|
|
console.log()
|
|
|
|
// get a sub matrix
|
|
// Matrix indexes are zero-based.
|
|
console.log('get a sub matrix')
|
|
const h = math.diag(math.range(1, 4))
|
|
print(h) // [[1, 0, 0], [0, 2, 0], [0, 0, 3]]
|
|
print(h.subset(math.index([1, 2], [1, 2]))) // [[2, 0], [0, 3]]
|
|
const i = math.range(1, 6)
|
|
print(i) // [1, 2, 3, 4, 5]
|
|
print(i.subset(math.index(math.range(1, 4)))) // [2, 3, 4]
|
|
console.log()
|
|
|
|
// resize a multi dimensional matrix
|
|
console.log('resizing a matrix')
|
|
const j = math.matrix()
|
|
let defaultValue = 0
|
|
j.resize([2, 2, 2], defaultValue)
|
|
print(j) // [[[0, 0], [0, 0]], [[0, 0], [0, 0]]]
|
|
print(j.size()) // [2, 2, 2]
|
|
j.resize([2, 2])
|
|
print(j) // [[0, 0], [0, 0]]
|
|
print(j.size()) // [2, 2]
|
|
console.log()
|
|
|
|
// setting a value outside the matrices range will resize the matrix.
|
|
// new elements will be initialized with zero.
|
|
console.log('set a value outside a matrices range')
|
|
const k = math.matrix()
|
|
k.subset(math.index(2), 6)
|
|
print(k) // [0, 0, 6]
|
|
console.log()
|
|
|
|
console.log('set a value outside a matrices range, setting other new entries to null')
|
|
const m = math.matrix()
|
|
defaultValue = null
|
|
m.subset(math.index(2), 6, defaultValue)
|
|
print(m) // [null, null, 6]
|
|
console.log()
|
|
|
|
// create ranges
|
|
console.log('create ranges')
|
|
print(math.range(1, 6)) // [1, 2, 3, 4, 5]
|
|
print(math.range(0, 18, 3)) // [0, 3, 6, 9, 12, 15]
|
|
print(math.range('2:-1:-3')) // [2, 1, 0, -1, -2]
|
|
print(math.factorial(math.range('1:6'))) // [1, 2, 6, 24, 120]
|
|
console.log()
|
|
|
|
/**
|
|
* 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))
|
|
}
|