* lib/matrix.rb: Optimizations

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@24968 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,7 @@
+Thu Sep 17 06:02:04 2009  Marc-Andre Lafortune  <ruby-core@marc-andre.ca>
+
+	* lib/matrix.rb: Optimizations
+
 Thu Sep 17 00:36:01 2009  Tanaka Akira  <akr@fsij.org>
 
 	* time.c (time_mdump): error message refined.

lib/matrix.rb

@@ -322,8 +322,8 @@ class Matrix
   #     => 1  4
   #        9 16
   #
-  def collect # :yield: e
-    rows = @rows.collect{|row| row.collect{|e| yield e}}
+  def collect(&block) # :yield: e
+    rows = @rows.collect{|row| row.collect(&block)}
     Matrix.rows(rows, false)
   end
   alias map collect
@@ -457,11 +457,9 @@ class Matrix
 
       rows = (0 ... row_size).collect {|i|
         (0 ... m.column_size).collect {|j|
-          vij = 0
-          column_size.times do |k|
-            vij += self[i, k] * m[k, j]
+          (0 ... column_size).inject(0) do |vij, k|
+            vij + self[i, k] * m[k, j]
           end
-          vij
         }
       }
       return Matrix.rows(rows, false)
@@ -667,11 +665,10 @@ class Matrix
     det = 1
     size.times do |k|
       if (akk = a[k][k]) == 0
-        i = k
-        loop do
-          return 0 if (i += 1) >= size
-          break unless a[i][k] == 0
-        end
+        i = (k+1 ... size).find {|i|
+          a[i][k] != 0
+        }
+        return 0 if i.nil?
         a[i], a[k] = a[k], a[i]
         akk = a[k][k]
         det *= -1
@@ -708,11 +705,10 @@ class Matrix
     det = 1
     size.times do |k|
       if a[k][k].zero?
-        i = k
-        loop do
-          return 0 if (i += 1) >= size
-          break unless a[i][k].zero?
-        end
+        i = (k+1 ... size).find {|i|
+          a[i][k] != 0
+        }
+        return 0 if i.nil?
         a[i], a[k] = a[k], a[i]
         det *= -1
       end
@@ -755,36 +751,21 @@ class Matrix
     rank = 0
     a_column_size.times do |k|
       if (akk = a[k][k]) == 0
-        i = k
-        exists = true
-        loop do
-          if (i += 1) >= a_column_size
-            exists = false
-            break
-          end
-          break unless a[i][k] == 0
-        end
-        if exists
+        i = (k+1 ... a_column_size).find {|i|
+          a[i][k] != 0
+        }
+        if i
           a[i], a[k] = a[k], a[i]
           akk = a[k][k]
         else
-          i = k
-          exists = true
-          loop do
-            if (i += 1) >= a_row_size
-              exists = false
-              break
-            end
-            break unless a[k][i] == 0
-          end
-          if exists
+          i = (k+1 ... a_row_size).find {|i|
+            a[k][i] != 0
+          }
+          next if i.nil?
           (k ... a_column_size).each do |j|
             a[j][k], a[j][i] = a[j][i], a[j][k]
           end
           akk = a[k][k]
-          else
-            next
-          end
         end
       end
 
@@ -840,11 +821,9 @@ class Matrix
   #     => 16
   #
   def trace
-    tr = 0
-    column_size.times do |i|
-      tr += @rows[i][i]
+    (0...column_size).inject(0) do |tr, i|
+      tr + @rows[i][i]
     end
-    tr
   end
   alias tr trace