diff options
Diffstat (limited to 'lib/matrix.rb')
| -rw-r--r-- | lib/matrix.rb | 29 |
1 files changed, 29 insertions, 0 deletions
diff --git a/lib/matrix.rb b/lib/matrix.rb index e0995c394f..7502e6ef8b 100644 --- a/lib/matrix.rb +++ b/lib/matrix.rb @@ -58,6 +58,7 @@ end # * #each_with_index # * #find_index # * #minor(*param) +# * #first_minor(row, column) # # Properties of a matrix: # * #diagonal? @@ -590,6 +591,34 @@ class Matrix new_matrix rows, [column_count - from_col, size_col].min end + # + # Returns the submatrix obtained by deleting the specified row and column. + # + # Matrix.diagonal(9, 5, -3, 4).first_minor(1, 2) + # => 9 0 0 + # 0 0 0 + # 0 0 4 + # + def first_minor(row, column) + raise RuntimeError, "first_minor of empty matrix is not defined" if empty? + + unless 0 <= row && row < row_count + raise ArgumentError, "invalid row (#{row.inspect} for 0..#{row_count - 1})" + end + + unless 0 <= column && column < column_count + raise ArgumentError, "invalid column (#{column.inspect} for 0..#{column_count - 1})" + end + + arrays = to_a + arrays.delete_at(row) + arrays.each do |array| + array.delete_at(column) + end + + new_matrix arrays, column_count - 1 + end + #-- # TESTING -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- #++ |