C++*********************************************************************
C
C    CCRS_3.F 
C      PGI BUG                                  FEB 10 2006 ArDean Leith
C      REAL CALCULATIONS                        FEB 11 2006 Bimal Rath
C      MOD PGI COMPILER BUG                     FEB 19 2008 ArDean Leith
C
C **********************************************************************
C=* FROM: SPIDER - MODULAR IMAGE PROCESSING SYSTEM.   AUTHOR: J.FRANK  *
C=* Copyright (C) 1985-2008  Health Research Inc.                      *
C=*                                                                    *
C=* HEALTH RESEARCH INCORPORATED (HRI),                                *   
C=* ONE UNIVERSITY PLACE, RENSSELAER, NY 12144-3455.                   *
C=*                                                                    *
C=* Email:  spider@wadsworth.org                                       *
C=*                                                                    *
C=* This program is free software; you can redistribute it and/or      *
C=* modify it under the terms of the GNU General Public License as     *
C=* published by the Free Software Foundation; either version 2 of the *
C=* License, or (at your option) any later version.                    *
C=*                                                                    *
C=* This program is distributed in the hope that it will be useful,    *
C=* but WITHOUT ANY WARRANTY; without even the implied warranty of     *
C=* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU  *
C=* General Public License for more details.                           *
C=*                                                                    *
C=* You should have received a copy of the GNU General Public License  *
C=* along with this program; if not, write to the                      *
C=* Free Software Foundation, Inc.,                                    *
C=* 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.      *
C=*                                                                    *
C **********************************************************************
C
C  CCRS_3(X,Y,O,LS,NSAM,NROW,NSLICE)
C
C  PURPOSE: CALCULATES CIRCULAR CROSCORRELATION, NON-POWER-OF-TWO 
C           DIMENSIONS
C  
C  PARAMETERS:   X,Y  FOURIER TRANSFORMS                       (SENT)
C                O    F(X*CONJG(Y))                            (RET.)
C                LS   NSAM+2-MOD(NSAM,2)                       (SENT)
C
C23456789012345678901234567890123456789012345678901234567890123456789012
C--*********************************************************************

        SUBROUTINE CCRS_3(X,Y,O, LS,NSAM,NROW,NSLICE)
	
C       REAL ::          X((NSAM+2-MOD(NSAM,2)),NROW,NSLICE)
C       ABOVE ON PGI COMPILER 7.1 FAILS TO COMPILE PROPERLY SOMETIMES

        REAL             :: X(LS,NROW,NSLICE)
        REAL             :: Y(LS,NROW,NSLICE)
        REAL             :: O(LS,NROW,NSLICE)

        DOUBLE PRECISION :: PI2

        PI2  = 8.0 * DATAN(1.0D0)
        ITMP = NSAM / 2
        SX   = PI2 * FLOAT(ITMP) / FLOAT(NSAM)
        ITMP = NROW / 2
        SY   = PI2 * FLOAT(ITMP) / FLOAT(NROW)
        ITMP = NSLICE / 2
        SZ   = PI2 * FLOAT(ITMP) / FLOAT(NSLICE)


Cc$omp   parallel do private(i,j,k,iy,iz,arg,argy,argz,tmpr,tmpi)

        DO K=1,NSLICE
           IZ = K - 1
           IF (IZ .GT. (NSLICE/2))  IZ = IZ - NSLICE
           ARGZ = SZ * IZ

           DO J=1,NROW
              IY = J - 1
              IF (IY .GT. (NROW/2))  IY = IY - NROW
              ARGY = SY * IY + ARGZ

              DO I=1,LS,2
                 ARG  = SX * (I-1)/2 + ARGY
		 TMPR =  X(I,J,K)   * Y(I,J,K)  + 
     &                   X(I+1,J,K) * Y(I+1,J,K)
		 TMPI =  X(I+1,J,K) * Y(I,J,K)  - 
     &                   X(I,J,K)   * Y(I+1,J,K)

		 O(I,J,K)   = TMPR * COS(ARG) - TMPI * SIN(ARG)
		 O(I+1,J,K) = TMPI * COS(ARG) + TMPR * SIN(ARG)
              ENDDO
           ENDDO
        ENDDO
	
        INS = -1
        CALL FMRS_3(O,NSAM,NROW,NSLICE,INS)

        END

#ifdef NEVER
		 OREAL = TMPR * COS(ARG) - TMPI * SIN(ARG)
		 OIMG  = TMPI * COS(ARG) + TMPR * SIN(ARG)
		 
		 O(I,J,K)   = OREAL
		 O(I+1,J,K) = OIMG		 
#endif