SUBROUTINE ZPTH(SUM,SUMSQ,NADDS,PTHRSH,PNSIG,PTA,STATUS)
C
C Module Number: 13.5.2
C
C Module Name: ZPTH
C
C Keyphrase:
C ----------
C Compute particle count threshholds
C
C Description:
C ------------
C  A particle count threshhold is computed for each diode by either:
C
C       1) average count rate for the diode + PTHRSH
C
C               or if PTHRSH is 0
C
C       2) average count rate for the diode + PNSIG * the standard deviation
C          of the count rate for the diode.
C
C
C FORTRAN Name: ZPTH.for
C
C
C Keywords of Accessed Files :
C --------------------------
C       NONE
C
C Modules Called:
C ---------------
C SDAS:
C       UMSPUT
C
C History:
C --------
C Version       Date      Author        Description
C   1           8/30/86  D. Lindler     Designed and coded
C   2           JAN 88  D. LINDLER      NEW SDAS I/O AND STANDARDS
C------------------------------------------------------------------------
C     INCLUDE FILE FOR THE IRAF77 FORTRAN INTERFACE TO THE IRAF VOS
C
C
C     FILE I/O ACCESS MODES
C
      INTEGER   RDONLY
      PARAMETER (RDONLY = 1)
      INTEGER   RDWRIT
      PARAMETER (RDWRIT = 2)
      INTEGER   WRONLY
      PARAMETER (WRONLY = 3)
      INTEGER   APPEND
      PARAMETER (APPEND = 4)
C
C     CODES FOR DATA TYPES
C
      INTEGER   TYBOOL
      PARAMETER (TYBOOL = 1)
      INTEGER   TYCHAR
      PARAMETER (TYCHAR = 2)
      INTEGER   TYINT
      PARAMETER (TYINT = 4)
      INTEGER   TYREAL
      PARAMETER (TYREAL = 6)
      INTEGER   TYDOUB
      PARAMETER (TYDOUB = 7)
C
C     UMSPUT DESTINATIONS -- CB, DAO, 4-SEP-87
C
      INTEGER STDOUT
      PARAMETER (STDOUT = 1)
      INTEGER STDERR
      PARAMETER (STDERR = 2)
C
C     UHDAS HEADER PARM TYPES -- CB, DAO, 5-SEP-87
C
      INTEGER GENHDR
      PARAMETER (GENHDR = 0)
      INTEGER IMSPEC
      PARAMETER (IMSPEC = 1)
C
C     THIS SECTION IS FOR PARAMETERS RELEVANT TO TABLE I/O.
C
C     THESE MAY BE SET BY UTPPTI AND/OR READ BY UTPGTI:
C
C                                       LENGTH OF ROW (UNIT = SIZE OF REAL)
      INTEGER   TBRLEN
      PARAMETER (TBRLEN = 1)
C                                       INCREASE ROW LENGTH
      INTEGER   TBIRLN
      PARAMETER (TBIRLN = 2)
C                                       NUMBER OF ROWS TO ALLOCATE
      INTEGER   TBALLR
      PARAMETER (TBALLR = 3)
C                                       INCREASE ALLOC NUM OF ROWS
      INTEGER   TBIALR
      PARAMETER (TBIALR = 4)
C                                       WHICH TYPE OF TABLE? (ROW OR COLUMN)
      INTEGER   TBWTYP
      PARAMETER (TBWTYP = 5)
C                                       MAXIMUM NUMBER OF USER PARAMETERS
      INTEGER   TBMXPR
      PARAMETER (TBMXPR = 6)
C                                       MAXIMUM NUMBER OF COLUMNS
      INTEGER   TBMXCL
      PARAMETER (TBMXCL = 7)
C                                       TYPE = ROW-ORDERED TABLE
      INTEGER   TBTYPR
      PARAMETER (TBTYPR = 11)
C                                       TYPE = COLUMN-ORDERED TABLE
      INTEGER   TBTYPC
      PARAMETER (TBTYPC = 12)
C
C     THESE MAY BE READ BY UTPGTI BUT MAY NOT BE SET:
C
C                                       NUMBER OF ROWS WRITTEN TO
      INTEGER   TBNROW
      PARAMETER (TBNROW = 21)
C
C     END IRAF77.INC
C
C INPUT PARAMETERS
C
        REAL    SUM(500)
C                                    --->SUM OF THE DATA FOR THE 500 SCIENCE DIODES
        REAL    SUMSQ(500)
C                                    --->SUM OF THE SQUARES OF THE DATA
        INTEGER NADDS(500)
C                                    --->NUMBER OF ADDS TO EACH POINT
        REAL    PTHRSH
C                                    --->THRESHOLD ABOVE AVERAGE
        REAL    PNSIG
C                                    --->NUMBER OF SIGMA ABOVE AVERAGE TO
C                                        USE IF PTHRSH=0
C
C OUTPUT PARAMETERS
C
        REAL    PTA(500)
C                                    --->THRESHOLD FOR EACH DIODE
        INTEGER STATUS
C
C LOCAL VARIABLES
C
        CHARACTER*130 MESS
        INTEGER I
        REAL    AVE,SIG
C
C LOOP ON EACH DIODE
C
        DO 100 I=1,500
                IF(NADDS(I).EQ.0)THEN
                        WRITE(MESS,99)I+6
C                                    --->6 DIODE OFFSET FOR SPECIAL DIODES
99                      FORMAT(' UNABLE TO COMPUTE PARTICLE THRESHOLD ',
     *                          ' FOR DIODE',I5)
                        CALL UMSPUT(MESS,STDOUT,0,STATUS)
                        PTA(I)=1.0E20
C                                    --->SET TO HIGH NUMBER (I.E.
C                                                DISABLE PARTICLE DETECTION)
                   ELSE
                        AVE=SUM(I)/NADDS(I)
C                                    --->AVERAGE COUNT RATE
                        IF(PTHRSH.GT.0)THEN
C                                    --->THRESHOLD SPECIFIED?
                           PTA(I)=AVE+PTHRSH
                         ELSE
C                                    --->USE PNSIG
                           SIG=SQRT(SUMSQ(I)/NADDS(I)-AVE*AVE)
                           PTA(I)=AVE+PNSIG*SIG
                        ENDIF
                ENDIF
100     CONTINUE
        STATUS=0
        RETURN
        END