function checkVectorTypeAndReturnLength (vec) {
    const s = size(vec)

    if (s.length === 1) { // 1D vector
      return s[0]
    } else if (s.length === 2) { // 2D vector
      if (s[0] === 1) { // row vector
        return s[1]
      } else if (s[1] === 1) { // col vector
        return s[0]
      } else {
        throw new TypeError('At least one of the arguments is not a vector.')
      }
    } else {
      throw new TypeError('Only one- or two-dimensional vectors are supported.')
    }
  }
Create a dense matrix from vectors as individual columns.
If you pass row vectors, they will be transposed (but not conjugated!)

Syntax:

   math.matrixFromColumns(...arr)
   math.matrixFromColumns(col1, col2)
   math.matrixFromColumns(col1, col2, col3)

Examples:

   math.matrixFromColumns([1, 2, 3], [[4],[5],[6]])
   math.matrixFromColumns(...vectors)

See also:

   matrix, matrixFromRows, matrixFromFunction, zeros

@param {... Array | Matrix} cols Multiple columns
@return { number[][] | Matrix } if at least one of the arguments is an array, an array will be returned