gistfile1.diff

diff --git a/lib/ruby/stdlib/matrix.rb b/lib/ruby/stdlib/matrix.rb
index fb98d09..b387069 100644
--- a/lib/ruby/stdlib/matrix.rb
+++ b/lib/ruby/stdlib/matrix.rb
@@ -368,14 +368,16 @@ class Matrix
   #
   # Returns element (+i+,+j+) of the matrix.  That is: row +i+, column +j+.
   #
+  NIL_ARY = []
+  NIL_ARY_PROC = proc {NIL_ARY}
   def [](i, j)
-    @rows.fetch(i){return nil}[j]
+    @rows.fetch(i, &NIL_ARY_PROC).at(j)
   end
   alias element []
   alias component []
 
   def []=(i, j, v)
-    @rows[i][j] = v
+    @rows.at(i)[j] = v
   end
   alias set_element []=
   alias set_component []=
@@ -961,21 +963,36 @@ class Matrix
       r = self * m
       return r.column(0)
     when Matrix
-      Matrix.Raise ErrDimensionMismatch if column_count != m.row_count
-
-      rows = Array.new(row_count) {|i|
-        Array.new(m.column_count) {|j|
-          (0 ... column_count).inject(0) do |vij, k|
-            vij + self[i, k] * m[k, j]
-          end
-        }
-      }
-      return new_matrix rows, m.column_count
+      return _multiply_matrix(m)
     else
       return apply_through_coercion(m, __method__)
     end
   end
 
+  private def _multiply_matrix(m)
+    Matrix.Raise ErrDimensionMismatch if column_count != m.row_count
+
+    m_column_count = m.column_count
+    rows = Array.new(row_count)
+    i = 0
+    while i < row_count
+      rows[i] = row = Array.new(m_column_count)
+      j = 0
+      while j < m_column_count
+        k = 0
+        vij = 0
+        while k < column_count
+          vij = vij + self[i, k] * m[k, j]
+          k += 1
+        end
+        row[j] = vij
+        j+=1
+      end
+      i += 1
+    end
+    return new_matrix rows, m.column_count
+  end
+
   #
   # Matrix addition.
   #   Matrix.scalar(2,5) + Matrix[[1,0], [-4,7]]