mathjs/test/unit-tests/function/matrix/column.test.js

import assert from 'assert'
import math from '../../../../src/defaultInstance.js'

const column = math.column
const matrix = math.matrix

describe('column', function () {
  const a = [
    [0, 2, 0, 0, 0],
    [0, 1, 0, 2, 4],
    [0, 0, 0, 0, 0],
    [8, 4, 0, 3, 0],
    [0, 0, 0, 6, 0]
  ]
  const m = matrix(a)

  it('should throw an error if the column is out of range', function () {
    assert.throws(function () {
      const r = column(m, 9)
      assert.deepStrictEqual(
        r.valueOf(), [[0], [0], [0], [0], [0]]
      )
    }, /IndexError: Index out of range \(9 > 4\)/)
  })

  it('should throw an error if the column is not an integer', function () {
    assert.throws(function () {
      const r = column(m, 'x')
      assert.deepStrictEqual(
        r.valueOf(), [[0], [0], [0], [0], [0]]
      )
    }, /Error: Cannot convert "x" to a number/)
  })

  it('should throw an error if the matrix does not have two dimensions', function () {
    assert.throws(function () {
      const m = matrix([[[1, 2, 3]]])
      const r = column(m, 0)
      assert.deepStrictEqual(
        r.valueOf(), [[0], [0], [0], [0], [0]]
      )
    }, /Error: Only two dimensional matrix is supported/)
  })

  it('should return the first matrix column', function () {
    const c = column(m, 0)
    assert.deepStrictEqual(
      c.valueOf(), [[0], [0], [0], [8], [0]]
    )
  })

  it('should return the first array column', function () {
    const c = column(a, 0)
    assert.deepStrictEqual(
      c.valueOf(), [[0], [0], [0], [8], [0]]
    )
  })

  it('should return the last matrix column', function () {
    const c = column(m, 4)
    assert.deepStrictEqual(
      c.valueOf(), [[0], [4], [0], [0], [0]]
    )
  })

  it('should return the last array column', function () {
    const c = column(a, 4)
    assert.deepStrictEqual(
      c.valueOf(), [[0], [4], [0], [0], [0]]
    )
  })

  it('should return an intermediate matrix column', function () {
    const c = column(m, 1)
    assert.deepStrictEqual(
      c.valueOf(), [[2], [1], [0], [4], [0]]
    )
  })

  it('should return an intermediate array column', function () {
    const c = column(a, 1)
    assert.deepStrictEqual(
      c.valueOf(), [[2], [1], [0], [4], [0]]
    )
  })

  it('should return an empty matrix column', function () {
    const c = column(m, 2)
    assert.deepStrictEqual(
      c.valueOf(), [[0], [0], [0], [0], [0]]
    )
  })

  it('should return an empty array column', function () {
    const c = column(a, 2)
    assert.deepStrictEqual(
      c.valueOf(), [[0], [0], [0], [0], [0]]
    )
  })
})