C ++********************************************************************
C   PRB1D.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
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C--*********************************************************************



        SUBROUTINE PRB1D(B,NPOINT,POS)

        DOUBLE PRECISION B(NPOINT),C2,C3

        NHALF  = NPOINT/2 + 1
        POS=0.0
        IF (NPOINT .EQ. 7) THEN
           C2 = 49.*B(1) + 6.*B(2) - 21.*B(3) - 32.*B(4) - 27.*B(5)
     1       - 6.*B(6) + 31.*B(7)
           C3 = 5.*B(1) - 3.*B(3) - 4.*B(4) - 3.*B(5) + 5.*B(7)
        ELSEIF (NPOINT .EQ. 5) THEN
           C2 = (74.*B(1) - 23.*B(2) - 60.*B(3) - 37.*B(4)
     1        + 46.*B(5) ) / (-70.)
           C3 = (2.*B(1) - B(2) - 2.*B(3) - B(4) + 2.*B(5) ) / 14.
        ELSEIF (NPOINT .EQ. 3) THEN
           C2 = (5.*B(1) - 8.*B(2) + 3.*B(3) ) / (-2.)
           C3 = (B(1) - 2.*B(2) + B(3) ) / 2.
        ELSEIF (NPOINT .EQ. 9) THEN
           C2 = (1708.*B(1) + 581.*B(2) - 246.*B(3) - 773.*B(4)
     1         - 1000.*B(5) - 927.*B(6) - 554.*B(7) + 119.*B(8)
     1         + 1092.*B(9) ) / (-4620.)
           C3 = (28.*B(1) + 7.*B(2) - 8.*B(3) - 17.*B(4) - 20.*B(5)
     1        - 17.*B(6) - 8.*B(7) + 7.*B(8) + 28.*B(9) ) / 924.
        ENDIF

        IF (C3.NE.0.0D0)  POS = C2/(2.*C3) - NHALF
        RETURN
        END