code: function _getColumns(matrix) {
    var cols = [];
    for (var i=0; i<matrix.size.columns; i++) {
      cols.push([]);
      for (var j=0; j<matrix.size.rows; j++)
        cols[i].push(matrix.values[i + j * matrix.size.columns]);
    }
    return cols;
  }
docs: Creates an array of the columns of a matrix
  
  @param {Matrix} matrix
  @returns {Array} columns array: two-dimensional