NetCDFRealVariable
initialize a NetCDFVariable either from file or scratch
Discussion
This function is not intended to be called directly by a
user. To create a new variable, the user should call
addVariable' or initVariable’ on the group or file.
To initialize a variable from file you must pass the group and variable id, e.g.
aVariable = NetCDFVariable(group,id=3);
To create a new variable, you must pass the group and the other required parameters
aVariable = NetCDFVariable(group,name=aName,attributes=someAttributes,type='double');
class(data)