SUBROUTINE MPAIR

PURPOSE
   PERFORM THE WILCOXON MATCHED-PAIRS SIGNED-RANKS TEST, GIVEN
   TWO VECTORS OF N OBSERVATIONS OF THE MATCHED SAMPLES.

USAGE
   CALL MPAIR (N,A,B,K,T,Z,P,D,E,L,IE)

DESCRIPTION OF PARAMETERS
   N - NUMBER OF OBSERVATIONS IN THE VECTORS A AND B
   A - INPUT VECTOR OF LENGTH N CONTAINING DATA FROM THE FIRST
       SAMPLE
   B - INPUT VECTOR OF LENGTH N CONTAINING DATA FROM THE SECOND
       SAMPLE
   K - OUTPUT VARIABLE CONTAINING THE NUMBER OF PAIRS OF THE
       MATCHED SAMPLES WHOSE DIFFERENCES ARE NON ZERO (0)
   T - OUTPUT VARIABLE CONTAINING THE SUM OF THE RANKS OF PLUS
       OR MINUS DIFFERENCES, WHICHEVER IS SMALLER
   Z - VALUE OF THE STANDARDIZED NORMAL SCORE COMPUTED FOR THE
       WILCOXON MATCHED-PAIRS SIGNED-RANKS TEST
   P - COMPUTED PROBABILITY OF OBTAINING A VALUE OF Z AS
       EXTREME AS THE ONE FOUND BY THE TEST
   D - WORKING VECTOR OF LENGTH N
   E - WORKING VECTOR OF LENGTH N
   L - WORKING VECTOR OF LENGTH N
   IE- 1, IF SAMPLES A AND B ARE IDENTICAL.
       0 OTHERWISE.  IF IE=1, THEN T=P=0, AND Z=-10**75

REMARKS
   THE COMPUTED PROBABILTY IS FOR A ONE-TAILED TEST.
   MULTIPLYING P BY 2 WILL GIVE THE VALUE FOR A TWO-TAILED
   TEST.

SUBROUTINES AND FUNCTIONS SUBPROGRAMS REQUIRED
   RANK
   NDTR

METHOD
   REFER TO DIXON AND MASSEY, AN INTRODUCTION TO STATISTICAL
   ANALYSIS (MC GRAW-HILL, 1957)