6.4 Expressions

In any input field, data can be entered in the form of expressions. Numbers and variables are special cases of expressions. An expression is typed in Fortran style and may contain any number of nested parenthesis. The standard intrinsic functions are also available (see next section). MOLPRO understands both arithmetic and logical expressions. The result of an arithmetic expression is a real (double precision) number. Internally, all integers are also converted to real numbers. The result of a logical expression is either .TRUE. or .FALSE.. Internally, .TRUE. is stored as a one (1.0), and .FALSE. as zero (0.0). Expressions may contain any number of variables.

The following standard operations can be performed :

expr + expr

Addition

expr - expr

Subtraction

expr * expr

Multiplication

expr / expr

Division

expr .OR. expr

Logical OR

expr .AND. expr

Logical AND

expr .XOR. expr

Exclusive OR

.NOT.expr

Logical NOT

expr .GT. expr

Greater Than

expr .EQ. expr

Equal

expr .LT. expr

Less Than

expr .GE. expr

Greater Equal

expr .LE. expr

Less Equal

expr .NE. expr

Not Equal

expr **expr

Exponentiation

expr ^ expr

Exponentiation

(expr)

Parenthesis (no effect)

-expr

Change sign

+expr

Keep sign (no effect)