This is documentation for Mathematica 5, which was
based on an earlier version of the Wolfram Language.

 Further Examples: Blank (_) Patterns, Rules, and Replacement This rule can be used to replace the logarithm of a power in the usual way. In[1]:= Out[1]= Rules are applied using the slash-dot operator. In[2]:= Out[2]= As an aside, this rule is not built into Mathematica because it is not correct in general. In[3]:= Out[3]= However, the built-in function PowerExpand does such transformations. In[4]:= Out[4]= In[5]:= Patterns in Function Definitions You can often simplify the definition of a function by putting the arguments in a suitable form and naming the important parts. In this case we are avoiding the use of [[]] (Part). In[6]:= To make this definition without pattern matching, you would need to use a module, local variables, conditionals, and some complicated constructions to get at the right pieces. In[7]:= In[8]:= Out[8]= We clear the definitions. In[9]:= Using FullForm The output you see from Mathematica is designed for human eyes. Expressions that look the same may be structurally different. FullForm reveals the internal representation of expressions. In[10]:= Out[10]//FullForm= In[11]:= Out[11]//FullForm= In[12]:= Out[12]//FullForm= In this example, notice that the second square root is not transformed to become 1/s. In[13]:= Out[13]= FullForm shows that the representation of the square root depends on whether it is in the numerator or the denominator. In[14]:= Out[14]//FullForm= In[15]:= Out[15]//FullForm= One rule is needed for each case, and these can be put together in a list. In[16]:= Out[16]=