This is documentation for Mathematica 3, which was
based on an earlier version of the Wolfram Language.
 Position Position[ expr , pattern ] gives a list of the positions at which objects matching pattern appear in expr. Position[ expr , pattern , levspec ] finds only objects that appear on levels specified by levspec. Example: Position[ 1+x^2, 5, x^4 , x^_]. Position[ expr , pattern ] tests all the subparts of expr in turn to try and find ones that match pattern. Position returns a list of positions in a form suitable for use in Extract, ReplacePart and MapAt. The form is different from the one used in Part. The default level specification for Position is {0, Infinity}, with Heads -> True. Position[ list , pattern , 1 , Heads -> False] finds positions only of objects that appear as complete elements of list. Level specifications are described in Section A.3.6. Position[ expr , pattern , levspec , n ] gives the positions of the first n parts of expr which match the pattern. See the Mathematica book: Section 1.8.5, Section 2.1.7, Section 2.2.4, Section 2.3.2. See also: Cases, Count, StringPosition, ReplaceList, Insert, Delete. Further Examples The symbol c occurs in the third position of this list. In[1]:= Out[1]= This gives the positions of the elements of the list that are manifestly powers. In[2]:= Out[2]= The head of the expression (List in position 0) and the first two elements of the expression (a and Pi) have head Symbol. In[3]:= Out[3]= In[4]:= Out[4]= In[5]:=