C ++********************************************************************
C                                                                      *
C ENER.F                                                               *
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 IMAGE_PROCESSING_ROUTINE
C
C        1         2         3         4         5         6         7
C23456789012345678901234567890123456789012345678901234567890123456789012
C --********************************************************************

        DOUBLE PRECISION FUNCTION  ENER(CIRC,LCIRC,NRING,NUMR,MODE)
        DIMENSION  CIRC(LCIRC)
        INTEGER  NUMR(3,NRING)
        DOUBLE PRECISION EN,PI,TQ,ENERT
        CHARACTER*1  MODE
        PI=4.0D0*DATAN(1.0D0)
        IF (MODE .EQ. 'F')  PI=2*PI
        ENERT=0.0             
        DO I=1,NRING
           EN=0.0
           TQ=2.0*REAL(NUMR(1,I))*PI/REAL(NUMR(3,I))
           DO J=NUMR(2,I)+2,NUMR(2,I)+NUMR(3,I)-1
              EN=EN+TQ*CIRC(J)*CIRC(J)
           ENDDO
           EN=EN+TQ*(CIRC(NUMR(2,I))**2+CIRC(NUMR(2,I)+1)**2)/2.0
           ENERT=ENERT+EN/REAL(NUMR(3,I))
        ENDDO
        ENER=ENERT
        END