Internal types used in particular for computing the average and centroid temporal aggregates.
The double2, double3, and double4 types are base types composed, respectively, of two, three, and four double values. The tdouble2, tdouble3, and tdouble4 types are the corresponding temporal types. The in/out functions of all these types are stubs since all access should be internal. These types are used for the transition function of the aggregates, where the first components of the doubleN values store the sum and the last one stores the count of the values. The final function computes the average from the doubleN values.
Create a double2 value from the double values
