--- a/AbstractNumberVector.st	Sun Feb 14 00:23:18 2016 +0100
+++ b/AbstractNumberVector.st	Sun Feb 14 17:08:04 2016 +0100
@@ -249,7 +249,7 @@
 !
 
 primAddScalar: aScalar
-    "low performace fallback: destructively add the scalar argument into the receiver."
+    "low performance fallback: destructively add the scalar argument into the receiver."
 
     1 to: self size do:[:i| self at: i put: (self at: i) + aScalar].
 !
@@ -386,6 +386,7 @@
 !AbstractNumberVector methodsFor:'vector arithmetic'!
 
 length
+    <resource: #obsolete>
     "Return the length of the receiver interpreted as vector
      (that is the length of the vector from 0.0 @ 0.0 @ ... @ 0.0
       to the point in the n-dimensional space represented by the receiver).
@@ -402,6 +403,7 @@
 !
 
 squaredLength
+    <resource: #obsolete>
     "Return the squared length of the receiver interpreted as vector.
      Obsolete: the name 'squaredLength' may lead to confusion.
                therefore renamed to squaredVectorLength"