floor and ceiling definitions are not code equations -- this enables trivial evaluation of floor and ceiling

--- a/src/HOL/Archimedean_Field.thy	Wed Jul 06 23:11:59 2011 +0200
+++ b/src/HOL/Archimedean_Field.thy	Thu Jul 07 23:33:14 2011 +0200
@@ -143,7 +143,7 @@
 
 definition
   floor :: "'a::archimedean_field \<Rightarrow> int" where
-  "floor x = (THE z. of_int z \<le> x \<and> x < of_int (z + 1))"
+  [code del]: "floor x = (THE z. of_int z \<le> x \<and> x < of_int (z + 1))"
 
 notation (xsymbols)
   floor  ("\<lfloor>_\<rfloor>")
@@ -274,7 +274,7 @@
 
 definition
   ceiling :: "'a::archimedean_field \<Rightarrow> int" where
-  "ceiling x = - floor (- x)"
+  [code del]: "ceiling x = - floor (- x)"
 
 notation (xsymbols)
   ceiling  ("\<lceil>_\<rceil>")