Namespaces
	CUDA

	LinearAlgebra

	MPI

	System

	Trilinos

Classes
struct	fixed_int_power

struct	fixed_int_power< a, 0 >

Functions
std::string	dealii_version_string ()

std::string	int_to_string (const unsigned int value, const unsigned int digits=numbers::invalid_unsigned_int)

template<typename number >
std::string	to_string (const number value, const unsigned int digits=numbers::invalid_unsigned_int)

unsigned int	needed_digits (const unsigned int max_number)

int	string_to_int (const std::string &s)

std::string	dim_string (const int dim, const int spacedim)

std::vector< int >	string_to_int (const std::vector< std::string > &s)

double	string_to_double (const std::string &s)

std::vector< double >	string_to_double (const std::vector< std::string > &s)

std::vector< std::string >	split_string_list (const std::string &s, const std::string &delimiter=",")

std::vector< std::string >	split_string_list (const std::string &s, const char delimiter)

std::vector< std::string >	break_text_into_lines (const std::string &original_text, const unsigned int width, const char delimiter= ' ')

bool	match_at_string_start (const std::string &name, const std::string &pattern)

std::pair< int, unsigned int >	get_integer_at_position (const std::string &name, const unsigned int position)

std::string	replace_in_string (const std::string &input, const std::string &from, const std::string &to)

std::string	trim (const std::string &input)

double	generate_normal_random_number (const double a, const double sigma)

template<int N, typename T >
T	fixed_power (const T t)

constexpr unsigned int	pow (const unsigned int base, const unsigned int iexp)

template<typename Iterator , typename T >
Iterator	lower_bound (Iterator first, Iterator last, const T &val)

template<typename Iterator , typename T , typename Comp >
Iterator	lower_bound (Iterator first, Iterator last, const T &val, const Comp comp)

std::vector< unsigned int >	reverse_permutation (const std::vector< unsigned int > &permutation)

std::vector< unsigned int >	invert_permutation (const std::vector< unsigned int > &permutation)

std::vector< unsigned long long int >	reverse_permutation (const std::vector< unsigned long long int > &permutation)

std::vector< unsigned long long int >	invert_permutation (const std::vector< unsigned long long int > &permutation)

template<typename T >
size_t	pack (const T &object, std::vector< char > &dest_buffer, const bool allow_compression=true)

template<typename T >
std::vector< char >	pack (const T &object, const bool allow_compression=true)

template<typename T >
T	unpack (const std::vector< char > &buffer, const bool allow_compression=true)

template<typename T >
T	unpack (const std::vector< char >::const_iterator &cbegin, const std::vector< char >::const_iterator &cend, const bool allow_compression=true)

template<typename T , int N>
void	unpack (const std::vector< char > &buffer, T(&unpacked_object)[N], const bool allow_compression=true)

template<typename T , int N>
void	unpack (const std::vector< char >::const_iterator &cbegin, const std::vector< char >::const_iterator &cend, T(&unpacked_object)[N], const bool allow_compression=true)

template<typename To , typename From >
std::unique_ptr< To >	dynamic_unique_cast (std::unique_ptr< From > &&p)

static::ExceptionBase &	ExcInvalidNumber2StringConversersion (unsigned int arg1, unsigned int arg2)

static::ExceptionBase &	ExcInvalidNumber (unsigned int arg1)

static::ExceptionBase &	ExcCantConvertString (std::string arg1)

Detailed Description

A namespace for utility functions that are not particularly specific to finite element computing or numerical programs, but nevertheless are needed in various contexts when writing applications.

Author: Wolfgang Bangerth, 2005

Function Documentation

std::string Utilities::dealii_version_string ( )

Return a string of the form "deal.II version x.y.z" where "x.y.z" identifies the version of deal.II you are using. This information is also provided by the DEAL_II_PACKAGE_NAME and DEAL_II_PACKAGE_VERSION preprocessor variables.

Definition at line 88 of file utilities.cc.

std::string Utilities::int_to_string	(	const unsigned int	value,
		const unsigned int	digits = `numbers::invalid_unsigned_int`
	)

Convert a number value to a string, with as many digits as given to fill with leading zeros.

If the second parameter is left at its default value, the number is not padded with leading zeros. The result is then the same as if the standard C function itoa() had been called.

When calling this function signed integers are implicitly converted to unsigned integers and long integers might experience an overflow.

Note: The use of this function is discouraged and users should use Utilities::to_string() instead. In its current implementation the function simply calls to_string<unsigned int>().

Definition at line 96 of file utilities.cc.

template<typename number >

std::string Utilities::to_string	(	const number	value,
		const unsigned int	digits = `numbers::invalid_unsigned_int`
	)

Convert a number value to a string, with digits characters. The string is padded with leading zeros, after a possible minus sign. Therefore the total number of padding zeros is digits minus any signs, decimal points and digits of value.

If the second parameter is left at its default value, the number is not padded with leading zeros. The result is then the same as if the boost function lexical_cast<std::string>() had been called.

Definition at line 105 of file utilities.cc.

unsigned int Utilities::needed_digits ( const unsigned int max_number )

Determine how many digits are needed to represent numbers at most as large as the given number.

Definition at line 180 of file utilities.cc.

int Utilities::string_to_int ( const std::string & s )

Given a string, convert it to an integer. Throw an assertion if that is not possible.

Definition at line 201 of file utilities.cc.

std::string Utilities::dim_string	(	const int	dim,
		const int	spacedim
	)

Return a string describing the dimensions of the object. Often, functions in the deal.II library as well as in user codes need to define a string containing the template dimensions of some objects defined using two template parameters: dim (the topological dimension of the object) and spacedim (the dimension of the embedding Euclidean space). Since in all deal.II classes, by default spacedim is equal to dimension, the above string is usually contracted to "<dim>", instead of "<dim,spacedim>". This function returns a string containing "dim" if dim is equal to spacedim, otherwise it returns "dim,spacedim".

Definition at line 170 of file utilities.cc.

std::vector< int > Utilities::string_to_int ( const std::vector< std::string > & s )

Given a list of strings, convert it to a list of integers. Throw an assertion if that is not possible.

Definition at line 229 of file utilities.cc.

double Utilities::string_to_double ( const std::string & s )

Given a string, convert it to an double. Throw an assertion if that is not possible.

Definition at line 240 of file utilities.cc.

std::vector< double > Utilities::string_to_double ( const std::vector< std::string > & s )

Given a list of strings, convert it to a list of doubles. Throw an assertion if that is not possible.

Definition at line 268 of file utilities.cc.

std::vector< std::string > Utilities::split_string_list	(	const std::string &	s,
		const std::string &	delimiter = `","`
	)

Given a string that contains text separated by a delimiter, split it into its components; for each component, remove leading and trailing spaces. The default value of the delimiter is a comma, so that the function splits comma separated lists of strings.

To make data input from tables simpler, if the input string ends in a delimiter (possibly followed by an arbitrary amount of whitespace), then this last delimiter is ignored. For example,

Utilities::split_string_list("abc; def; ghi; ", ';');

yields the same 3-element list of output {"abc","def","ghi"} as you would get if the input had been

Utilities::split_string_list("abc; def; ghi", ';');

or

Utilities::split_string_list("abc; def; ghi;", ';');

As a consequence of this rule, a call like

Utilities::split_string_list(" ; ", ';');

yields a one-element list. Because of the trimming of whitespace, the single element is the empty string.

This function can digest the case that the delimiter is a space. In this case, it returns all words in the string. Combined with the rules above, this implies that

Utilities::split_string_list("abc def ghi ", ' ');

yields again the 3-element list of output {"abc","def","ghi"} from above despite the presence of space at the end of the string. Furthermore,

Utilities::split_string_list(" ", ' ');

yields an empty list regardless of the number of spaces in the string.

Definition at line 279 of file utilities.cc.

std::vector< std::string > Utilities::split_string_list	(	const std::string &	s,
		const char	delimiter
	)

Specialization of split_string_list() for the case where the delimiter is a single char.

Definition at line 324 of file utilities.cc.

std::vector< std::string > Utilities::break_text_into_lines	(	const std::string &	original_text,
		const unsigned int	width,
		const char	delimiter = `' '`
	)

Take a text, usually a documentation or something, and try to break it into individual lines of text at most width characters wide, by breaking at positions marked by delimiter in the text. If this is not possible, return the shortest lines that are longer than width. The default value of the delimiter is a space character. If original_text contains newline characters (
), the string is split at these locations, too.

Definition at line 333 of file utilities.cc.

bool Utilities::match_at_string_start	(	const std::string &	name,
		const std::string &	pattern
	)

Return true if the given pattern string appears in the first position of the string.

Definition at line 413 of file utilities.cc.

std::pair< int, unsigned int > Utilities::get_integer_at_position	(	const std::string &	name,
		const unsigned int	position
	)

Read a (signed) integer starting at the position in name indicated by the second argument, and return this integer as a pair together with how many characters it takes up in the string.

If no integer can be read at the indicated position, return (-1,numbers::invalid_unsigned_int)

Definition at line 428 of file utilities.cc.

std::string Utilities::replace_in_string	(	const std::string &	input,
		const std::string &	from,
		const std::string &	to
	)

Return a string with all occurrences of from in input replaced by to.

Definition at line 124 of file utilities.cc.

std::string Utilities::trim ( const std::string & input )

Return a string with all standard whitespace characters (including '\t', '\n', and '\r') at the beginning and end of input removed.

Definition at line 143 of file utilities.cc.

double Utilities::generate_normal_random_number	(	const double	a,
		const double	sigma
	)

Generate a random number from a normalized Gaussian probability distribution centered around a and with standard deviation sigma. The returned number will be different every time the function is called.

This function is reentrant, i.e., it can safely be called from multiple threads at the same time. In addition, each thread will get the same sequence of numbers every time. On the other hand, if you run Threads::Task objects via the Threading Building Blocks, then tasks will be assigned to mostly random threads, and may get a different sequence of random numbers in different runs of the program, since a previous task may already have consumed the first few random numbers generated for the thread you're on. If this is a problem, you need to create your own random number generator objects every time you want to start from a defined point.

Note: Like the system function rand(), this function produces the same sequence of random numbers every time a program is started. This is an important property for debugging codes, but it makes it impossible to really verify statistical properties of a code. For rand(), you can call srand() to "seed" the random number generator to get different sequences of random numbers every time a program is called. However, this function does not allow seeding the random number generator. If you need this, as above, use one of the C++ or BOOST facilities.

Definition at line 470 of file utilities.cc.

template<int N, typename T >

T Utilities::fixed_power ( const T t )

inline

Calculate a fixed power, provided as a template argument, of a number.

This function provides an efficient way to calculate things like t^N where N is a known number at compile time.

Use this function as in fixed_power<dim> (n).

Definition at line 912 of file utilities.h.

constexpr unsigned int Utilities::pow	(	const unsigned int	base,
		const unsigned int	iexp
	)

A replacement for std::pow that allows compile-time calculations for constant expression arguments.

Definition at line 353 of file utilities.h.

template<typename Iterator , typename T >

Iterator Utilities::lower_bound	(	Iterator	first,
		Iterator	last,
		const T &	val
	)

inline

Optimized replacement for std::lower_bound for searching within the range of column indices. Slashes execution time by approximately one half for the present application, partly because the binary search is replaced by a linear search for small loop lengths.

Another reason for this function is rather obscure: when using the GCC libstdc++ function std::lower_bound, complexity is O(log(N)) as required. However, when using the debug version of the GCC libstdc++ as we do when running the testsuite, then std::lower_bound tests whether the sequence is in fact partitioned with respect to the pivot 'value' (i.e. in essence that the sequence is sorted as required for binary search to work). However, verifying this means that the complexity of std::lower_bound jumps to O(N); we call this function O(N) times below, making the overall complexity O(N**2). The consequence is that a few tests with big meshes completely run off the wall time limit for tests and fail with the libstdc++ debug mode

This function simply makes the assumption that the sequence is sorted, and we simply don't do the additional check.

Definition at line 939 of file utilities.h.

template<typename Iterator , typename T , typename Comp >

Iterator Utilities::lower_bound	(	Iterator	first,
		Iterator	last,
		const T &	val,
		const Comp	comp
	)

inline

The same function as above, but taking an argument that is used to compare individual elements of the sequence of objects pointed to by the iterators.

Definition at line 948 of file utilities.h.

std::vector< unsigned int > Utilities::reverse_permutation ( const std::vector< unsigned int > & permutation )

Given a permutation vector (i.e. a vector \(p_0\ldots p_{N-1}\) where each \(p_i\in [0,N)\) and \(p_i\neq p_j\) for \(i\neq j\)), produce the reverse permutation \(q_i=N-1-p_i\).

Definition at line 489 of file utilities.cc.

std::vector< unsigned int > Utilities::invert_permutation ( const std::vector< unsigned int > & permutation )

Given a permutation vector (i.e. a vector \(p_0\ldots p_{N-1}\) where each \(p_i\in [0,N)\) and \(p_i\neq p_j\) for \(i\neq j\)), produce the inverse permutation \(q_0\ldots q_{N-1}\) so that \(q_{p_i}=p_{q_i}=i\).

Definition at line 503 of file utilities.cc.

std::vector< unsigned long long int > Utilities::reverse_permutation ( const std::vector< unsigned long long int > & permutation )

Given a permutation vector (i.e. a vector \(p_0\ldots p_{N-1}\) where each \(p_i\in [0,N)\) and \(p_i\neq p_j\) for \(i\neq j\)), produce the reverse permutation \(q_i=N-1-p_i\).

Definition at line 525 of file utilities.cc.

std::vector< unsigned long long int > Utilities::invert_permutation ( const std::vector< unsigned long long int > & permutation )

Given a permutation vector (i.e. a vector \(p_0\ldots p_{N-1}\) where each \(p_i\in [0,N)\) and \(p_i\neq p_j\) for \(i\neq j\)), produce the inverse permutation \(q_0\ldots q_{N-1}\) so that \(q_{p_i}=p_{q_i}=i\).

Definition at line 539 of file utilities.cc.

template<typename T >

size_t Utilities::pack	(	const T &	object,
		std::vector< char > &	dest_buffer,
		const bool	allow_compression = `true`
	)

Given an arbitrary object of type T, use boost::serialization utilities to pack the object into a vector of characters and append it to the given buffer. The number of elements that have been added to the buffer will be returned. The object can be unpacked using the Utilities::unpack function below.

If the library has been compiled with ZLIB enabled, then the output buffer can be compressed. This can be triggered with the parameter allow_compression, and is only of effect if ZLIB is enabled.

If many consecutive calls with the same buffer are considered, it is recommended for reasons of performance to ensure that its capacity is sufficient.

Author: Timo Heister, Wolfgang Bangerth, 2017.

Definition at line 1046 of file utilities.h.

template<typename T >

std::vector< char > Utilities::pack	(	const T &	object,
		const bool	allow_compression = `true`
	)

Creates and returns a buffer solely for the given object, using the above mentioned pack function.

If the library has been compiled with ZLIB enabled, then the output buffer can be compressed. This can be triggered with the parameter allow_compression, and is only of effect if ZLIB is enabled.

Author: Timo Heister, Wolfgang Bangerth, 2017.

Definition at line 1114 of file utilities.h.

template<typename T >

T Utilities::unpack	(	const std::vector< char > &	buffer,
		const bool	allow_compression = `true`
	)

Given a vector of characters, obtained through a call to the function Utilities::pack, restore its content in an object of type T.

This function uses boost::serialization utilities to unpack the object from a vector of characters, and it is the inverse of the function Utilities::pack().

The allow_compression parameter denotes if the buffer to read from could have been previously compressed with ZLIB, and is only of effect if ZLIB is enabled.

Note: Since no arguments to this function depend on the template type T, you must manually specify the template argument when calling this function.; If you want to pack() or unpack() arrays of objects, then the following works:
double array[3] = {1,2,3};
std::vector<char> buffer = Utilities::pack(array);
However, the converse does not:
array = Utilities::unpack<double[3]>(buffer);
This is because C++ does not allow functions to return arrays. Consequently, there is a separate unpack() function for arrays, see below.

Author: Timo Heister, Wolfgang Bangerth, 2017.

Definition at line 1186 of file utilities.h.

template<typename T >

T Utilities::unpack	(	const std::vector< char >::const_iterator &	cbegin,
		const std::vector< char >::const_iterator &	cend,
		const bool	allow_compression = `true`
	)

Same unpack function as above, but takes constant iterators on (a fraction of) a given packed buffer of type std::vector<char> instead.

The allow_compression parameter denotes if the buffer to read from could have been previously compressed with ZLIB, and is only of effect if ZLIB is enabled.

Author: Timo Heister, Wolfgang Bangerth, 2017.

Definition at line 1124 of file utilities.h.

template<typename T , int N>

void Utilities::unpack	(	const std::vector< char > &	buffer,
		T(&)	unpacked_object[N],
		const bool	allow_compression = `true`
	)

Given a vector of characters, obtained through a call to the function Utilities::pack, restore its content in an array of type T.

This function uses boost::serialization utilities to unpack the object from a vector of characters, and it is the inverse of the function Utilities::pack().

The allow_compression parameter denotes if the buffer to read from could have been previously compressed with ZLIB, and is only of effect if ZLIB is enabled.

Note: This function exists due to a quirk of C++. Specifically, if you want to pack() or unpack() arrays of objects, then the following works:
double array[3] = {1,2,3};
std::vector<char> buffer = Utilities::pack(array);
However, the converse does not:
array = Utilities::unpack<double[3]>(buffer);
This is because C++ does not allow functions to return arrays. The current function therefore allows to write
Utilities::unpack(buffer, array);
Note that unlike the other unpack() function, it is not necessary to explicitly specify the template arguments since they can be deduced from the second argument.

Author: Timo Heister, Wolfgang Bangerth, 2017.

Definition at line 1250 of file utilities.h.

template<typename T , int N>

void Utilities::unpack	(	const std::vector< char >::const_iterator &	cbegin,
		const std::vector< char >::const_iterator &	cend,
		T(&)	unpacked_object[N],
		const bool	allow_compression = `true`
	)

Same unpack function as above, but takes constant iterators on (a fraction of) a given packed buffer of type std::vector<char> instead.

The allow_compression parameter denotes if the buffer to read from could have been previously compressed with ZLIB, and is only of effect if ZLIB is enabled.

Author: Timo Heister, Wolfgang Bangerth, 2017.

Definition at line 1194 of file utilities.h.

template<typename To , typename From >

std::unique_ptr<To> Utilities::dynamic_unique_cast ( std::unique_ptr< From > && p )

Convert an object of type std::unique_ptr<From> to an object of type std::unique_ptr<To>, where it is assumed that we can cast the pointer to From to a pointer to To using a dynamic_cast – in other words, we assume that From and To are connected through a class hierarchy, and that the object pointed to is in fact of a type that contains both a From and a To. An example is if either To is derived from From or the other way around.

The function throws an exception of type std::bad_cast if the dynamic_cast does not succeed. This is the same exception you would get if a regular dynamic_cast between object types (but not pointer types) does not succeed.

An example of how this function works is as follows:

// A base class. Assume that it has virtual
// functions so that dynamic_cast can work.
class B
{
  ...
};
// A derived class
class D : public B
{
  ...
};
// A factory function
std::unique_ptr<B> create_object (...)
{
  ...
}
void foo (...)
{
  std::unique_ptr<B> b = create_object (...);
  // Assume that we know for some reason that the object above must
  // have created a D object but returned it as a std::unique_ptr<B>.
  // In order to access the D functionality, we need to cast the
  // pointer. Use the equivalent to dynamic_cast:
  std::unique_ptr<D> d = dynamic_unique_cast<D>(std::move(b));
  // If the object really was a D, then 'd' now points to it. Note
  // also that in accordance with the semantics of std::unique_ptr,
  // it was necessary to std::move the 'b' object, and indeed 'b'
  // now no longer points to anything -- ownership has been
  // transferred to 'd'!

Note: This function does not try to convert the Deleter objects stored by std::unique_ptr objects. The function therefore only works if the deleter objects are at their defaults, i.e., if they are of type std::default_delete<To> and std::default_delete<From>.

Definition at line 630 of file utilities.h.

Namespaces

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Detailed Description

Function Documentation