Provided by: python3-ffc_2019.1.0.post0-2_all bug

NAME

       FFC - the FEniCS Form Compiler

SYNOPSIS

       ffc  [-h]  [-V] [-S] [-v] [-s] [-e] [-l language] [-r representation] [-f option] [-O] [-q
       quadrature-rule] ... input.ufl ...

DESCRIPTION

       Compile multilinear forms into efficient low-level code.

       The FEniCS Form Compiler FFC accepts as input one or more files, each  specifying  one  or
       more  multilinear  forms,  and  compiles the given forms into efficient low-level code for
       automatic assembly of the tensors representing the multilinear forms. In  particular,  FFC
       compiles a pair of bilinear and linear forms defining a variational problem into code that
       can be used to efficiently assemble the corresponding linear system.

       By default, FFC generates code according to the UFC  specification  version  1.0  (Unified
       Form-assembly Code, see http://www.fenics.org/) but this can be controlled by specifying a
       different output language (option -l). It is also possible to add new output languages  to
       FFC.

       For  a  full  description  of  FFC, including a specification of the form language used to
       define the multilinear forms, see the FFC user manual available on the  FEniCS  web  page:
       http://www.fenics.org/

OPTIONS

       -h, --help
              Display help text and exit.

       -V, --version
              Display version number and exit.

       -S, --signature
              Display UFC signature and exit.

       -v, --verbose
              Verbose mode, more output is printed. Conflicts with -s.

       -s, --silent
              Silent mode, no output is printed. Conflicts with -v.

       -e, --error-control
              Error  control  mode,  a  set  of  additional  forms useful for goal-oriented error
              control is generated and compiled.

       -l language, --language language
              Specify output language, one of 'ufc' (default) or 'dolfin' (UFC with a small layer
              of DOLFIN-specific bindings).

       -r representation, --representation representation
              Specify  representation for precomputation and code generation, one of 'quadrature'
              (default) or 'tensor'.

       -f option
              Specify code generation options. The list  of  options  available  depends  on  the
              specified   language   (format).   Current   options   include   -fblas,  -fno-foo,
              -fprecision=n,           -fprecompute_basis_const,           -fprecompute_ip_const,
              -fsimplify_expressions,   -feliminate_zeros,  -fquadrature_degree=n  and,  -fsplit,
              -fno_ferari, described in detail below.

       -f blas
              Generate code that uses BLAS to compute tensor products.  This option is  currently
              ignored,  but  can  be  used  to  reduce  the  code  size  when  the BLAS option is
              (re-)implemented in future versions.

       -f no-foo
              Don't generate code for UFC function with name 'foo'. Typical options include -fno-
              evaluate_basis  and  -fno-evaluate_basis_derivatives  to  reduce  the  size  of the
              generated code when these functions are not needed.

       -f precision=n
              Set the number of significant digits to n in the generated code.  The default value
              of n is 15.

       -f precompute_basis_const
              Optimisation  option  for  quadrature  representation.  This  option  is ignored if
              optimisation  is  not  used  (see   -O   option),   and   it   also   implies   the
              -fprecompute_ip_const  option. This option will generate code that precompute terms
              which are constant in the loops involving basis indices.   This  can  result  in  a
              reduction  of the operation count and thereby improve the runtime efficiency of the
              generated code. However, the improvements depends on the GCC  compiler  options  as
              well as the characteristics of the variational form.

       -f precompute_ip_const
              Like the -fprecompute_basis_const option with the only difference that code will be
              generated  to  compute  terms  which  are  constant  in  the  loops  involving  the
              integration points only.

       -f simplify_expressions
              Optimisation  option  for  quadrature  representation.  This  option  is ignored if
              optimisation is not used (see -O option). Before  simplifying  the  expressions  to
              compute  the  local  element  tensor,  they  are  expanded in order to identify and
              precompute terms which are  constant  with  respect  to  geometry  and  integration
              points.  This  operation  can be very expensive since it involves creating many new
              terms which might result in memory being exhausted.

       -f eliminate_zeros
              Optimisation option for  quadrature  representation.  This  option  is  ignored  if
              optimisation  is  not used (see -O option). Tables containing basis function values
              will be compressed such that they only contain non zero values.  This  will  reduce
              the  loop  ranges  and  thereby  the  number  of operations, but since a mapping is
              introduced, in order to insert values  correctly  into  the  element  matrix,  some
              overhead  is  introduced.  This  optimisation  option  is usually most effective in
              combination with one of the other optimisation options.

       -f quadrature_degree=n
              Will generate a  quadrature  rule  accurate  up  to  degree  n  regardless  of  the
              polynomial  degree  of  the  form.  This option is only valid for UFL forms and the
              specified degree will apply to ALL terms of the given form for which no degree  has
              been  specified  through  metadata!  As  default  FFC  will  determine  the  degree
              automatically from the form.

       -f split
              Generate separate files for declarations and the implementation.

       -f no_ferari
              Skip FErari optimizations, even if the -O flag is set. This only  has  effect  when
              the  tensor representation is used. This option can be used in combination with the
              -O flag to avoid potentially very long compilation times by instructing FFC to only
              optimize when the quadrature representation is used.

       -O, --optimize
              Generate optimized code with a lower operation count compared to non-optimized code
              for the assembly of the local element tensor. This will  in  general  increase  the
              run-time performance of the code. If the representation (see -r option) is 'tensor'
              then FFC will use FErari optimizations.  This option requires FErari and should  be
              used  with  caution  since  it  may be very costly (at compile-time) for other than
              simple forms.  If the representation  is  'quadrature'  the  compile-time  increase
              tends  to  be  much  less drastic compared to FErari for very complex forms. The -O
              option for quadrature representation turns on the following optimisation flags:

              -fsimplify_expressions -feliminate_zeros

       -o directory, --output-directory directory
              Specify the directory where the generated files should be written to.  The  default
              output directory is the current ('.') directory.

       -q rule, --quadrature-rule rule
              Specify  the  quadrature rule that should be used when integrating the forms.  This
              will affect both tensor and quadrature representation. Currently, available options
              are  'default'  and  'canonical'.   The  'default'  option  covers hand implemented
              quadrature rules for triangles and tetrahedra with a degree of precision less  than
              or  equal  to six.  The 'canonical' option relies on FIAT to compute the quadrature
              rule which is based on the Gauss--Legendre--Jacobi rule mapped onto simplices.   By
              default,  FFC will try to use the 'default' option as this will typically result in
              the most efficient code being generated. If this is not possible (if the polynomial
              degree of the integrand is larger than six, or if the cell is not one of 'triangle'
              or 'tetrahedron'), FFC will automatically apply the 'canonical' rule. If the number
              of  integration  points  used  by  the  'canonical'  rule  is too big for efficient
              computation, the option -fquadrature_degree can be used.

       BUGS

       See https://fenicsproject.org/support/ for channels to send comments,
              questions, bug reports etc.

AUTHOR

       Written by Anders Logg (logg@simula.no) with help from  Kristian  ├ślgaard,  Marie  Rognes,
       Garth N. Wells and many others.

                                                                                           FFC(1)