ffc(1)

NAME

FFC - the FEniCS Form Compiler

SYNOPSIS

ffc  [-h]  [-v] [-d] [-s] [-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 efficent 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.

-d, --debug

Debug mode, more output is printed. Conflicts with -s.

-s, --silent

Silent mode, no output is printed. Conflicts with -d.

-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 -fprecision=n, -fquadrature_points=n, -fsplit, -fblas and -fno-foo, described in detail below.

-f precision=n

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

-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 quadrature_points=n

Will generate n quadrature points in each spatial direction regardless of the polynomial degree of the form. This option is only valid for the standard FFC forms i.e., *.form files, not UFL forms. The specified number of points will apply to ALL terms of the given form! As default FFC will determine the number of quadrature points needed for exact representation of the form.

-f split

Generate separate files for declarations and the implementation.

-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.

-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. However, this option is currently ignored. 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.

-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, no quadrature rules has been implemented so the default from FIAT will be used.

BUGS

Send comments, questions, bug reports etc. to ffc-dev@fenics.org.

AUTHOR

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

FFC(1)