Bugs in Matrix#rank


#1

I think I found some bugs in Matrix#rank

ruby -rmatrix -e’p Matrix[[7,0], [1,0], [2,0]].rank’
…/matrix.rb:761:in `/’: nil can’t be coerced into Fixnum (TypeError)

ruby -rmatrix -e’p Matrix[[7,0], [1,0], [2,1]].rank’
…/matrix.rb:761:in `/’: nil can’t be coerced into Fixnum (TypeError)

Fix (?):
change
exists = true
begin
if (i += 1) > a_column_size - 1 # line 731
exists = false
break
end
end while a[i][k] == 0

to
exists = true
begin
if (i += 1) > a_row_size - 1
exists = false
break
end
end while a[i][k] == 0

and

      exists = true
      begin
        if (i += 1) > a_row_size - 1  # line 743
          exists = false
          break
        end
      end while a[k][i] == 0

to

      exists = true
      begin
        if (i += 1) > a_column_size - 1
          exists = false
          break
        end
      end while a[k][i] == 0

The error seems to be caused by using loop indices up to row/column
size for column/row indices, which causes some swaps with nil values.

version:

ruby -v
ruby 1.8.5 (2006-08-25) [i386-mingw32]