PairDistance Subroutine

SUBROUTINE PairDistance &
!
(stations)


IMPLICIT NONE

!Arguments with intent (in):
TYPE (ObservationalNetwork), INTENT(IN) :: stations

!Local declarations
  INTEGER (KIND = short) :: i, j
  REAL (KIND = float) :: average
  
!---------------------------end of declarations--------------------------------

  
!allocate variables
ALLOCATE ( dist_pairs(stations % countObs,stations % countObs))


! Compute distance among stations and experimental variance
average = 0.
dist_pairs = 0.

DO i = 1, stations % countObs
    average = average + stations % obs (i) % value
    DO j = 1, stations % countObs
        
        IF ( i == j) CYCLE !skip same point pairs, distance is zero
        
        IF ( j < i) CYCLE !this pair is already in the vector; pair(4,2) is the same as pair(2,4)
        
        point1 % northing = stations % obs (i) % xyz % northing  
        point1 % easting = stations % obs (i) % xyz % easting 
          
        point2 % northing = stations % obs (j) % xyz % northing  
        point2 % easting = stations % obs (j) % xyz % easting
                
        dist_pairs(i,j) = Distance (point1,point2)       
        
    END DO
END DO 

average = average / stations % countObs

!compute experimental variance
expVar = 0.
DO i = 1, stations % countObs
    expVar = expVar + ( stations % obs (i) % value - average ) ** 2.
END DO
expVar = expVar / stations % countObs
  
RETURN
END SUBROUTINE PairDistance