Declaration: 
MeanVarVector (Data: TDoubleArray; First, Last: integer; var Mean, Variance: double): integer; 
Calculates the mean and the variance of the data contained in the array Data, using all values from First to Last (the array Data has 0based indices). If First is greater than Last then First and Last are automatically exchanged.
The function returns the following error codes:
0 ... everything is OK
1 ... First and/or Last are out of range
2 ... the number of values is too low (minimum of 3 values required)

