method

minor

v2_5_5 - Show latest stable - 0 notes - Class: Matrix

minor(*param) public

Returns a section of the matrix. The parameters are either:

start_row, nrows, start_col, ncols; OR
row_range, col_range

Matrix.diagonal(9, 5, -3).minor(0..1, 0..2)
  => 9 0 0
     0 5 0

Like Array#[], negative indices count backward from the end of the row or column (-1 is the last element). Returns nil if the starting row or column is greater than row_count or column_count respectively.

Show source

# File lib/matrix.rb, line 545
  def minor(*param)
    case param.size
    when 2
      row_range, col_range = param
      from_row = row_range.first
      from_row += row_count if from_row < 0
      to_row = row_range.end
      to_row += row_count if to_row < 0
      to_row += 1 unless row_range.exclude_end?
      size_row = to_row - from_row

      from_col = col_range.first
      from_col += column_count if from_col < 0
      to_col = col_range.end
      to_col += column_count if to_col < 0
      to_col += 1 unless col_range.exclude_end?
      size_col = to_col - from_col
    when 4
      from_row, size_row, from_col, size_col = param
      return nil if size_row < 0 || size_col < 0
      from_row += row_count if from_row < 0
      from_col += column_count if from_col < 0
    else
      raise ArgumentError, param.inspect
    end

    return nil if from_row > row_count || from_col > column_count || from_row < 0 || from_col < 0
    rows = @rows[from_row, size_row].collect{|row|
      row[from_col, size_col]
    }
    new_matrix rows, [column_count - from_col, size_col].min
  end

minor

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