The logical-IF statement is best regarded as a special case of the IF-block when it only contains one statement. Thus:
IF(E .NE. 0.0) THEN
RECIPE = 1.0 / E
END IF
can be replaced by a single logical-IF statement: IF(E .NE. 0.0) RECIPE = 1.0 / E
The general form of the logical-IF statement is:
IF( logical-expression ) statement
The statement is executed only if the logical expression has a true
value. Any executable statement can follow except DO, IF,
ELSE IF, ELSE, END IF, or END.