XL Fortran for AIX 8.1  Language Reference  Introduction to
Expressions and Assignment  An expression is a data reference or
a computation, and is formed from operands, operators, and
parentheses. An expression, when evaluated, produces a value,
which has a type, a shape, and possibly type parameters.  An
operand is either a scalar or an array. An operator is either
intrinsic or defined. A unary operation has the form:  operator
operand  A binary operation has the form:  operand1 operator
operand2  where the two operands are shape-conforming. If one
operand is an array and the other is a scalar, the scalar is
treated as an array of the same shape as the array, and every
element of the array has the value of the scalar.  Any
expression contained in parentheses is treated as a data entity.
Parentheses can be used to specify an explicit interpretation of
an expression. They can also be used to restrict the alternative
forms of the expression, which can help control the magnitude
and accuracy of intermediate valu