DATE     94/01/10

    Opérateur CER3                             See also :CERC 
    --------------

   GEO1 = CER3 (N1)  POIN1 POIN2 POIN3  ('DINI' DENS1) ('DFIN' DENS2) ;

    Description :
    ____________

    The CER3 operator enables the user to construct an arc of a 
 circle from three points.

    Contents :
    __________

    POIN1 |
    POIN2 | : points used to define the arc of the circle 
    POIN3 |   (POINT type)

    N1      : number of generated elements (ENTIER type)

    DENS1 | : densities associated with the points POIN1 and POIN3 
    DENS2 |   (FLOTTANT type)

    GEO1    : arc of the circle (MAILLAGE type)


    Note :
    _______

    If N1 is not specified, the number of generated elements as well
as their size will be computed according to the extreme point densities.
    If N1 is specified and positive, N1 elements of equal length
 will be generated.
    If N1 is negative, N1 elements will be generated and their  
 size will be computed according to the extreme point densities.  
    
    If the densities associated with the POIN1 and POIN3 points are 
 inaccurate, they may be increased. The accurate value of the initial
 point will be mentioned after the 'DINI' key word, that of the 
 third point will be mentioned after the 'DFIN' key word.

   If a LIG1 line is given instead of the POIN1 point (or POIN3), 
 this line will be extended as far as the POIN3 point (the line
 begins at the POIN3 point).

    If the POIN3 point is not given, the first point of the
LIG1 line will be taken into account, which permits to close this
line.