C ++********************************************************************
C                                                                      *
C                                                                      *
C                                                                      *
C **********************************************************************
C=* FROM: SPIDER - MODULAR IMAGE PROCESSING SYSTEM.   AUTHOR: J.FRANK  *
C=* Copyright (C) 1985-2005  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                                                                      *
C                                                                      *
C  PURPOSE:                                                            *
C     FIND THE SHIFT BETWEEN POINTS AND SHIFT XYPTS
C                                                                      *
C  PARAMETERS:                                                         *
C                                                                      *
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C***********************************************************************

      SUBROUTINE MRSHIFT(PRJ,XYPTS,SHIFT,PTACTIVE,NTVW,NTPT)

      PARAMETER (LV=300)
      PARAMETER (LS=256)

      LOGICAL    PTACTIVE(LS,LV)
      DIMENSION  XYPTS(2,LS,LV),PRJ(2,LS,LV)
      DIMENSION  SHIFT(2,LS)


      DO IVIEW=1,NTVW
	DO J=1,2
	   SHIFT(J,IVIEW) = 0.0
	   NT = 0
	   DO I=1,NTPT
	      IF (PTACTIVE(I,IVIEW))  THEN
                 SHIFT(J,IVIEW) = SHIFT(J,IVIEW) - XYPTS(J,I,IVIEW)+
     &                           PRJ(J,I,IVIEW)
	         NT=NT+1
	      ENDIF
	   ENDDO

	   SHIFT(J,IVIEW) = SHIFT(J,IVIEW)/NT

           DO  I=1,NTPT
              IF (PTACTIVE(I,IVIEW))
     &		XYPTS(J,I,IVIEW) = XYPTS(J,I,IVIEW)+SHIFT(J,IVIEW)
	   ENDDO
         ENDDO
      ENDDO
      END