Relational expressions consist of two or more expressions whose
  values are compared to determine whether the relationship stated by
  the relational operator is satisfied.  The expression is reduced to
  a logical value (true or false).

  The following are relational operators:

        Operator         Meaning
        ------------------------------------------
         .LT. or <       Less than
         .LE. or <=      Less than or equal to
         .EQ. or ==      Equal to
         .NE. or /=      Not equal to
         .GT. or >       Greater than
         .GE. or >=      Greater than or equal to

  NOTE: Expressions of COMPLEX data type can use only
        .EQ.  and .NE. operators.