C++*********************************************************************
C
C  ASTA.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   ASTA
C
C IMAGE_PROCESSING_ROUTINE
C
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C--*********************************************************************

        SUBROUTINE  ASTA(X,N,RI,ABA,KLP)

        DIMENSION   X(N,N)
        DOUBLE PRECISION  ABA

C       ESTIMATE AVERAGE OUTSIDE THE CIRCLE
        R  =RI*RI
        NC =N/2+1
        DO   J=1,N
           T=J-NC
           XX=T*T
           DO   I=1,N
              T=I-NC
              IF (XX+T*T.GT.R)    THEN
                 ABA=ABA+DBLE(X(I,J))
                 KLP=KLP+1
              ENDIF
           ENDDO
        ENDDO
        RETURN
        END