CTITLEMCROSS -- COMPUTES CROSS CORRELATION                              00000010
C***********************************************************************
C                 COPYRIGHT ATLANTIC RICHFIELD COMPANY 1991            *
C***********************************************************************
CA       AUTHOR                 D. D. THOMPSON                          00000020
CA       DESIGNER               D. D. THOMPSON                          00000030
CA       LANGUAGE               FORTRAN 77                              00000040
CA       SYSTEM                 IBM & CRAY                              00000041
CA       WRITTEN                1972                                    00000050
C        REVISED                MO-DA-YR                                00000060
C        REVISED                05-20-85 TWH. ADAPTED TO IBM & CRAY.    00000061
C                                                                       00000070
CA                                                                      00000080
CA                                                                      00000090
CA       CALL MCROSS (NX, X, NY, Y, IT, R)                              00000100
CA             INPUT  NX      = LENGTH OF X                        I4   00000110
CA             INPUT  X       = INPUT VECTOR                       R4   00000120
CA             INPUT  NY      = LENGTH OF Y                        I4   00000130
CA             INPUT  Y       = INPUT VECTOR                       R4   00000140
CA             INPUT  IT      = NUMBER OF LAGS TO COMPUTE IN       I4   00000150
CA                              ADDITION TO ZERO LAG                    00000160
CA             OUTPUT R       = RETURNED CORRELATION VECTOR        R4   00000170
CA                                                                      00000180
CA                                                                      00000190
CA                                                                      00000200
CA              THIS ROUTINE COMPUTES THE CROSS CORRELATION             00000210
CA          BETWEEN TWO INPUT VECTORS.                                  00000220
CA                                                                      00000230
CA                                                                      00000240
CA                                                                      00000250
C                                                                       00000260
C    SUBROUTINES CALLED: NONE                                           00000270
C                                                                       00000280
C     EJECT                                                             00000290
C                                                                       00000300
      SUBROUTINE MCROSS (NX, X, NY, Y, IT, R)                           00000310
CAEND                                                                   00000320
C                                                                       00000330
      DIMENSION X(1),Y(1),R(1)                                          00000340
      ITP1=IT+1                                                         00000350
C                                                                       00000360
          DO                                                        20  00000370
     *    I=1,ITP1                                                      00000380
          ITOW=I-1                                                      00000390
          IB=NX                                                         00000400
          IF(NX+ITOW.GT.NY) IB=NY-ITOW                                  00000410
          Q=0.                                                          00000420
C                                                                       00000430
              DO                                                    10  00000440
     *        J=1,IB                                                    00000450
C                                                                       00000460
   10         Q=Q+X(J)*Y(J+ITOW)                                        00000470
C                                                                       00000480
   20     R(I)=Q/IB                                                     00000490
C                                                                       00000500
      RETURN                                                            00000510
      END                                                               00000520