                               ERACEL

                  refines cell parameters + zeropoint
                         or refines wavelength,
                    is a local version from CELREF 
                              (see below)
 
      This 32 bits PC program works on Win95 (or Win NT).
      
      Double-click on eracel.exe from the Windows explorer or
      open a DOS box in the directory conaining eracel.exe and
      type "eracel", then answer to the questions. In any case
      the program opens a DOS box.
 
      The first question asks for the data filename. This should
      be a .dat file.

      Care, the program is not always polite with users not giving
      high quality data (some comments are in french).
  
      The ERACEL.ZIP package contains a test file : eracel.dat
      that you should try. The result appears in a .imp file.
      Data should be entered in 2-theta, however the result is given
      in theta (the zeropoint too). The zeropoint is given as a value
      to be subtracted from the observed angular values. Care to change
      the sign if you use this zeropoint in another program which adds
      the zeropoint to experimental data (for instance ITO and some local
      versions of DICVOL and TREOR).

      The FORTRAN code is available. The executable was built from the
      MSVC++2.00 compiler applied to eracel.c obtained from eracel.f
      the the f2c translator.

      Armel Le Bail  armel@fluo.univ-lemans.fr  November 1996

      
                       PAREMETERS DEFINITIONS

C.....******************************************************************
C.....
C.....     PROGRAM   *** CELREF ***                         7/10/78
C.....
C.....     AUTHORS : JEAN LAUGIER & ALAIN FILHOL    20/10/78
C.....
C.....     REFINEMENT OF THE CELL PARAMETERS
C.....                OF THE ZEROPOINT
C.....                OF THE WAVELENGTH
C.....     STARTING FROM 2-THETA DIFFRACTING BRAGG ANGLES
C.....
C.....     METHOD : NON-LINEAR LEAST SQUARES 
C.....
C.....     DATA :
C.....      LINES
C.....        1- CARD COMMENT          FORMAT(16A5)
C.....        2- INDIC,IFIN                 FORMAT(2I)
C.....           INDIC  : CONSTRAINT FOR THE REFINEMENT
C.....                  =  0/1/2 FOR (A,B,C INDEPENDENTS)/(A=B=C)/(A=B)
C.....           IFIN   : MAXIMUM NUMBER OF REFINEMENT CYCLES
C.....
C.....        3- B(2),B(1)                       FORMAT(2F)
C.....           B(2)   : WAVELENGHT
C.....           B(1)   : ZEROPOINT IN THETA DEGREES TO BE SUBTRACTED TO THE
C.....                    EXPERIMENTAL DATA
C.....
C.....        4- AFI(2),AFI(1)                   FORMAT(2F)
C.....           AFI(2) : 0/1 REFINE (NO)/(YES)   THE WAVELENGTH
C.....           AFI(1) :  "    "         "       THE ZEROPOINT
C.....
C.....        5- B(3 to 8)                        FORMAT(6F)
C.....           B(3)   : PARAMETER A
C.....           B(4)   : PARAMETER B
C.....           B(5)   : PARAMETER C
C.....           B(6)   : ANGLE ALPHA
C.....           B(7)   : ANGLE BETA
C.....           B(8)   : ANGLE GAMMA
C.....
C.....        6- AFI(3 to 8)                      FORMAT(6F)
C.....           AFI(3 to 8) : 0/1 FOR REFINING (NO)/(YES)
C.....                         THE CELL PARAMETERS
C.....
C.....        7 to 7+NR- H,K,L, 2-THETA              FORMAT(3I,F)
C.....          ("NR" NUMBER OF OBSERVATIONS)
C.....          (THE LAST CARD SHOULD BE : H,K,L=0 0 0)
C.....           H,K,L  : MILLER INDICES
C.....           2-THETA  : DIFFRACTING ANGLE
C.....
C.....*****************************************************************
C
C
