This is documentation for Mathematica 3, which was
based on an earlier version of the Wolfram Language.
 Equal lhs == rhs returns True if lhs and rhs are identical. lhs == rhs is used to represent a symbolic equation, to be manipulated using functions like Solve. lhs == rhs returns True if lhs and rhs are identical expressions. lhs == rhs returns False if lhs and rhs are determined to be unequal by comparisons between numbers or other raw data, such as strings. Approximate numbers are considered equal if they differ in at most their last two decimal digits. 2 == 2. gives True. == == gives True if all the are equal. Equal[ e ] gives True. For exact numeric quantities, Equal internally uses numerical approximations to establish inequality. This process can be affected by the setting of the global variable \$MaxExtraPrecision. In StandardForm and InputForm, lhs == rhs can be input as lhs \[Equal] rhs or lhsrhs. See the Mathematica book: Section 1.5.5, Section 1.5.6. See also: SameQ, Unequal, Order. Further Examples For comparison, SameQ (===) checks whether the expressions are identical in form. In[1]:= Out[1]= Equal will return unevaluated if it cannot determine that the right-hand side and left-hand side are identical. SameQ is more assertive; use it if you need a function that will return False. In[2]:= Out[2]=