The shape and mapping of an array are defined by an ordered list of
orthogonal index ranges.
The types of array elements are restricted to one of the Java
primitive types (cf, F77). There is a separate (sub)class of array
for each primitive type.
ArrayInt a = new ArrayInt(x, y) ;
ArrayFloat b = new ArrayFloat(y, x) ;
ArrayDouble c = new ArrayDouble(y) ;
ArrayDouble d = new ArrayDouble(z) ;
