Relational Operators

The following relational operators deliver a logical result:

• .GT. -- greater than.
• .GE. -- greater than or equal to.
• .LE. -- less than or equal to.
• .LT. -- less than.
• .NE. -- not equal to.
• .EQ. -- equal to.

for example,

     i .GT. 12

is an expression delivering a .TRUE. or .FALSE. result.

These above operators are equivalent to the following:

• > -- greater than.
• >= -- greater than or equal to.
• <= -- less than or equal to.
• < -- less than.
• /= -- not equal to.
• = -- equal to.

for example,

     i > 12

Both sets of symbols may be used in a single statement.

Relational operators:

• compare the values of two operands.
• deliver a logical result.
• can be applied to numeric operands (restrictions on COMPLEX which can only use .EQ. and .NE.).
• can be applied to default CHARACTER objects -- both objects are made to be the same length by padding the shorter with blanks. Operators refer to ASCII order (see Appendix ).
• cannot be applied to LOGICAL objects, for example,

      (bool .NE. .TRUE.)

  is not a valid expression but,

      (.NOT.bool)

  is.
• are used (in scalar) form in IF statements (see Section 2.1.1) and elementally in the WHERE statement (see Section 3.1.17).

Consider,

    bool = i.GT.j
    IF (i.EQ.j) c = D
    WHERE (a.NE.0) a = 1/a

The example demonstrates,

• simple logical assignment using a relational operator,
• an IF statement using a relational operator,
• a WHERE statement using a relational operator (in an array context).