Description:
The routine uses the
QUICKSORT algorithm to sort an array of values into descending order. The “median of three”
modification is included to reduce the likelihood of encountering the worst-case behaviour of
QUICKSORT.
The routine exists for types REAL (x=R), DOUBLE PRECISION (x=D), and INTEGER (x=I).
Invocation
CALL PDA_QSDx( EL, X )
Arguments
EL = INTEGER (Given)
The number of
elements of X to be sorted.
X( EL ) = TYPE (Given and Returned)
The array to be sorted.
References
Sedgwick, R., 1988, Algorithms (Addison-Wesley).
Timing
If N elements are to be
sorted, the average time goes as N*ln(N). The worst-case time goes as N**2.
Copyright
Copyright
(C) 1992 Science & Engineering Research Council