simple-squiggle

A restricted subset of Squiggle
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matrices.js (2917B)

      1 // matrices
      2 
      3 // load math.js (using node.js)
      4 const math = require('..')
      5 
      6 // create matrices and arrays. a matrix is just a wrapper around an Array,
      7 // providing some handy utilities.
      8 console.log('create a matrix')
      9 const a = math.matrix([1, 4, 9, 16, 25])
     10 print(a) // [1, 4, 9, 16, 25]
     11 const b = math.matrix(math.ones([2, 3]))
     12 print(b) // [[1, 1, 1], [1, 1, 1]]
     13 print(b.size()) // [2, 3]
     14 
     15 // the Array data of a Matrix can be retrieved using valueOf()
     16 const array = a.valueOf()
     17 print(array) // [1, 4, 9, 16, 25]
     18 
     19 // Matrices can be cloned
     20 const clone = a.clone()
     21 print(clone) // [1, 4, 9, 16, 25]
     22 console.log()
     23 
     24 // perform operations with matrices
     25 console.log('perform operations')
     26 print(math.sqrt(a)) // [1, 2, 3, 4, 5]
     27 const c = [1, 2, 3, 4, 5]
     28 print(math.factorial(c)) // [1, 2, 6, 24, 120]
     29 console.log()
     30 
     31 // create and manipulate matrices. Arrays and Matrices can be used mixed.
     32 console.log('manipulate matrices')
     33 const d = [[1, 2], [3, 4]]
     34 print(d) // [[1, 2], [3, 4]]
     35 const e = math.matrix([[5, 6], [1, 1]])
     36 print(e) // [[5, 6], [1, 1]]
     37 
     38 // set a submatrix.
     39 // Matrix indexes are zero-based.
     40 e.subset(math.index(1, [0, 1]), [[7, 8]])
     41 print(e) // [[5, 6], [7, 8]]
     42 const f = math.multiply(d, e)
     43 print(f) // [[19, 22], [43, 50]]
     44 const g = f.subset(math.index(1, 0))
     45 print(g) // 43
     46 console.log()
     47 
     48 // get a sub matrix
     49 // Matrix indexes are zero-based.
     50 console.log('get a sub matrix')
     51 const h = math.diag(math.range(1, 4))
     52 print(h) // [[1, 0, 0], [0, 2, 0], [0, 0, 3]]
     53 print(h.subset(math.index([1, 2], [1, 2]))) // [[2, 0], [0, 3]]
     54 const i = math.range(1, 6)
     55 print(i) // [1, 2, 3, 4, 5]
     56 print(i.subset(math.index(math.range(1, 4)))) // [2, 3, 4]
     57 console.log()
     58 
     59 // resize a multi dimensional matrix
     60 console.log('resizing a matrix')
     61 const j = math.matrix()
     62 let defaultValue = 0
     63 j.resize([2, 2, 2], defaultValue)
     64 print(j) // [[[0, 0], [0, 0]], [[0, 0], [0, 0]]]
     65 print(j.size()) // [2, 2, 2]
     66 j.resize([2, 2])
     67 print(j) // [[0, 0], [0, 0]]
     68 print(j.size()) // [2, 2]
     69 console.log()
     70 
     71 // setting a value outside the matrices range will resize the matrix.
     72 // new elements will be initialized with zero.
     73 console.log('set a value outside a matrices range')
     74 const k = math.matrix()
     75 k.subset(math.index(2), 6)
     76 print(k) // [0, 0, 6]
     77 console.log()
     78 
     79 console.log('set a value outside a matrices range, setting other new entries to null')
     80 const m = math.matrix()
     81 defaultValue = null
     82 m.subset(math.index(2), 6, defaultValue)
     83 print(m) // [null, null, 6]
     84 console.log()
     85 
     86 // create ranges
     87 console.log('create ranges')
     88 print(math.range(1, 6)) // [1, 2, 3, 4, 5]
     89 print(math.range(0, 18, 3)) // [0, 3, 6, 9, 12, 15]
     90 print(math.range('2:-1:-3')) // [2, 1, 0, -1, -2]
     91 print(math.factorial(math.range('1:6'))) // [1, 2, 6, 24, 120]
     92 console.log()
     93 
     94 /**
     95  * Helper function to output a value in the console. Value will be formatted.
     96  * @param {*} value
     97  */
     98 function print (value) {
     99   const precision = 14
    100   console.log(math.format(value, precision))
    101 }