102 lines
2.8 KiB
JavaScript
102 lines
2.8 KiB
JavaScript
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// matrices
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// load math.js (using node.js)
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const math = require('..')
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// create matrices and arrays. a matrix is just a wrapper around an Array,
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// providing some handy utilities.
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console.log('create a matrix')
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const a = math.matrix([1, 4, 9, 16, 25])
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print(a) // [1, 4, 9, 16, 25]
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const b = math.matrix(math.ones([2, 3]))
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print(b) // [[1, 1, 1], [1, 1, 1]]
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print(b.size()) // [2, 3]
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// the Array data of a Matrix can be retrieved using valueOf()
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const array = a.valueOf()
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print(array) // [1, 4, 9, 16, 25]
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// Matrices can be cloned
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const clone = a.clone()
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print(clone) // [1, 4, 9, 16, 25]
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console.log()
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// perform operations with matrices
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console.log('perform operations')
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print(math.sqrt(a)) // [1, 2, 3, 4, 5]
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const c = [1, 2, 3, 4, 5]
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print(math.factorial(c)) // [1, 2, 6, 24, 120]
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console.log()
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// create and manipulate matrices. Arrays and Matrices can be used mixed.
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console.log('manipulate matrices')
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const d = [[1, 2], [3, 4]]
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print(d) // [[1, 2], [3, 4]]
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const e = math.matrix([[5, 6], [1, 1]])
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print(e) // [[5, 6], [1, 1]]
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// set a submatrix.
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// Matrix indexes are zero-based.
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e.subset(math.index(1, [0, 1]), [[7, 8]])
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print(e) // [[5, 6], [7, 8]]
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const f = math.multiply(d, e)
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print(f) // [[19, 22], [43, 50]]
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const g = f.subset(math.index(1, 0))
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print(g) // 43
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console.log()
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// get a sub matrix
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// Matrix indexes are zero-based.
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console.log('get a sub matrix')
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const h = math.diag(math.range(1, 4))
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print(h) // [[1, 0, 0], [0, 2, 0], [0, 0, 3]]
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print(h.subset(math.index([1, 2], [1, 2]))) // [[2, 0], [0, 3]]
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const i = math.range(1, 6)
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print(i) // [1, 2, 3, 4, 5]
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print(i.subset(math.index(math.range(1, 4)))) // [2, 3, 4]
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console.log()
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// resize a multi dimensional matrix
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console.log('resizing a matrix')
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const j = math.matrix()
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let defaultValue = 0
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j.resize([2, 2, 2], defaultValue)
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print(j) // [[[0, 0], [0, 0]], [[0, 0], [0, 0]]]
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print(j.size()) // [2, 2, 2]
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j.resize([2, 2])
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print(j) // [[0, 0], [0, 0]]
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print(j.size()) // [2, 2]
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console.log()
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// setting a value outside the matrices range will resize the matrix.
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// new elements will be initialized with zero.
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console.log('set a value outside a matrices range')
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const k = math.matrix()
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k.subset(math.index(2), 6)
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print(k) // [0, 0, 6]
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console.log()
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console.log('set a value outside a matrices range, setting other new entries to null')
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const m = math.matrix()
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defaultValue = null
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m.subset(math.index(2), 6, defaultValue)
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print(m) // [null, null, 6]
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console.log()
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// create ranges
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console.log('create ranges')
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print(math.range(1, 6)) // [1, 2, 3, 4, 5]
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print(math.range(0, 18, 3)) // [0, 3, 6, 9, 12, 15]
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print(math.range('2:-1:-3')) // [2, 1, 0, -1, -2]
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print(math.factorial(math.range('1:6'))) // [1, 2, 6, 24, 120]
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console.log()
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/**
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* Helper function to output a value in the console. Value will be formatted.
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* @param {*} value
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*/
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function print (value) {
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const precision = 14
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console.log(math.format(value, precision))
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}
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