Provided by: felt_3.06-9_i386 bug

NAME

       corduroy - element mesh generation description file format

DESCRIPTION

       The  corduroy(4fe) file format is used by the corduroy(1fe) application
       for describing the desired element mesh generation.  In  general  white
       space  is  unimportant  in a file, arbitrary numeric expressions may be
       used, and case of keywords is unimportant.  As per standard convention,
       boldface  items  represent  keywords,  italicized  items  represent the
       syntax of the grammar, and items in brackets are  optional.   The  file
       syntax is shown below.

              [ initialization ]
              [ generators ]
              end

   Initialization
       The  initialization  section  occurs  first in the file if present.  It
       defines parameters common to  all  generators  and  has  the  following
       syntax.

              start-node = expression
              start-element = expression
              constraint = name
              material = name

       The  default  start-node  and start-element is one.  If a constraint is
       given  then  the  name  will  be  assigned  to  the  generated   nodes.
       Similarly, if a material is given then the name will be assigned to the
       generated elements.

   Generators
       The generators  section  contains  specifications  for  generating  the
       elements  and  the  associated  nodes.   The  section has the following
       syntax.

              [ line-generator ]
              [ grid-generator ]
              [ quadrilateral-grid-generator ]
              [ brick-grid-generator ]
              [ triangular-mesh-generator ]

   Lines
       A line-generator specifies the generation of elements along a  line  in
       three dimensions.  The generator has the following syntax.

              [ start = triple ]
              [ end = triple ]
              [ number = expression ]
              [ rule = linear | log ]
              [ element-type = name ]

       where a triple has one of the following forms:

              ( expression , expression , expression )
              ( expression , expression )

       If  the  z-coordinate  of a triple is not specified then the previously
       specified z-coordinate is used.  The initial  default  z-coordinate  is
       zero.   The  start  and  end  triples  define  the  starting and ending
       coordinates of the line respectively.  The number of elements along the
       line  is specified by number.  The rule assignment controls whether the
       elements are linearly or logarithmically distributed  along  the  line.
       The  element-type  specifies the type of elements to be generated.  The
       type of the element defined by name must be a linear element.

   Grids
       A grid-generator specifies the generation of elements within  a  three-
       dimensional grid.  The generator has the following syntax.

              [ start = triple ]
              [ end = triple ]
              [ x-number = expression ]
              [ y-number = expression ]
              [ z-number = expression ]
              [ x-rule = linear | log ]
              [ y-rule = linear | log ]
              [ z-rule = linear | log ]
              [ element-type = name ]

       The start and end triples define the diagonally opposite corners of the
       grid.  The x-number, y-number, and  z-number  assignments  specify  the
       number  of  elements  along  the  x,  y, and z dimensions respectively.
       Similarly, the x-rule, y-rule, and z-rule assignments  specify  whether
       the  elements are to be generated linearly or logarithmically along the
       x, y, and z dimensions respectively.  The type of the element specified
       by name must be a linear element.

   Quadrilateral Grids
       A  quadrilateral-grid-generator  specifies  the generation of four-node
       planar elements within a two-dimensional grid.  The generator  has  the
       following syntax.

              [ start = pair ]
              [ end = pair ]
              [ x-number = expression ]
              [ y-number = expression ]
              [ x-rule = linear | log ]
              [ y-rule = linear | log ]
              [ element-type = name ]

       The  start  and end pairs define the diagonally opposite corners of the
       grid.  The x-number, and y-number assignments  specify  the  number  of
       elements  along the x and y dimensions respectively.  Similarly, the x-
       rule, and y-rule assignments specify whether the  elements  are  to  be
       generated  linearly  or  logarithmically  along the x and y dimensions,
       respectively.  The type of the element specified  by  name  must  be  a
       four-node planar element.

   Brick Grids
       A brick-grid-generator specifies the generation of solid brick elements
       within a three-dimensional  grid.   The  generator  has  the  following
       syntax.

              [ start = triple ]
              [ end = triple ]
              [ x-number = expression ]
              [ y-number = expression ]
              [ z-number = expression ]
              [ x-rule = linear | log ]
              [ y-rule = linear | log ]
              [ z-rule = linear | log ]
              [ element-type = name ]

       The start and end triples define the diagonally opposite corners of the
       grid.  The x-number, y-number, and  z-number  assignments  specify  the
       number  of  elements  along  the  x,  y, and z dimensions respectively.
       Similarly, the x-rule, y-rule, and z-rule assignments  specify  whether
       the  elements are to be generated linearly or logarithmically along the
       x, y, and z dimensions respectively.  The type of the element specified
       by name must be an eight node solid element.

   Triangular meshes
       A  triangular-mesh-generator  specifies  the  generation  of triangular
       elements  within  a  two-dimensional  mesh.   The  generator  has   the
       following syntax.

              [ tolin = expression ]
              [ angspc = expression ]
              [ angtol = expression ]
              [ dmin = expression ]
              [ kappa = expression ]
              [ min = expression ]
              [ max = expression ]
              [ boundary = [ pair-list ] ]
              [ hole = [ pair-list ] ]
              [ element-type = name ]

       where a pair has the following form:

              ( expression , expression )

       The tolin, angspc, angtol, dmin, kappa, min, and max parameters control
       the specifics of the mesh generation and are discussed  in  the  user’s
       guide.  The element type specified by name must be a planar, triangular
       element.  The boundary assignment specifies the boundary points of  the
       mesh  which must be given in counter-clockwise order.  The pair-list is
       a sequence of pairs.  A hole assignment specifies  a  hole  within  the
       mesh and similarly the points must be given in counter-clockwise order.
       Unlike other assignments,  a  hole  assignment  does  not  overwrite  a
       previous  assignment  but instead adds to it.  Thus, more than hole can
       be specified  by  repeating  the  hole  assignment  as  many  times  as
       necessary.

AUTHOR

       The   corduroy   file   format   was   developed   by  Jason  I.  Gobat
       (jgobat@mit.edu) and Darren C. Atkinson (atkinson@ucsd.edu).

SEE ALSO

       corduroy(1fe), felt(4fe).