Utility.cpp File Reference

#include "Utility.hpp"

Functions
double *	vector2array (const std::vector< double > &a)
	copy the content of the vector to an array, which can be directly written to the h5 file.
double *	vector2array (const std::vector< double > &a, const unsigned N)
	copy the content of the vector to an array, specified by size.
int *	vector2array (const std::vector< int > &a)
double **	vector2array (const std::vector< double > &data, const unsigned M, const unsigned N)
	copy the content of the vector to a MxN 2-D array.
void	deleteArray (double **data)
	Free the memory space created by vector2array()
void	deleteArray (double *data)
	Free the memory space created by vector2array()
std::vector< std::vector < double > >	vector2vector (const std::vector< double > &a, const int N, const int M)
std::vector< double >	array2vector (const double *in, const int size)
std::vector< std::vector < double > >	array2vector (const double *a, const int N, const int M)
	create a 2-D array from a 1-D array specified by N rows and M columns.
double	str2num (const std::string &s)
	Use the std::istd::stringstream to perform the conversion.
std::string	num2str (const double x)
	Use the std::ostd::stringstream to perform the conversion.
std::string	getRandomFileName (std::string &prefix)
	Generate a h5 file name in format of "prefix_year_month_day_hour_minute_random.h5".
int	getNextPower (int N, int base)
void	writeToTxtFile (const std::string file_name, const std::vector< double > &data)
void	writeToTxtFile (const std::string file_name, const std::vector< std::vector< double > > &data)
double	bandwidthToGaussianStdDev (unsigned bandwidth_defn, double bandwidth)
std::vector< double >	solveTridiagonalSystem (const std::vector< double > &a, const std::vector< double > &b, const std::vector< double > &c, const std::vector< double > &d)
	solve Ax = d problem, where A is a tri-diagonal system specified by its lower, main, and upper diagonal.
void	convertIndex (const int index, const int nZ, int j, int k)
	Convert the integer index to the indices of the two-dimensional vector.
void	convertIndex (const int index, const int nY, const int nZ, int i, int j, int k)
	Convert the integer index to the indices of the three-dimensional vector.
std::vector< int >	findEqual (const std::vector< double > &reference, const double x)
	Find the index of the elements that are equal to x.
std::vector< int >	findEqual (const std::vector< std::vector< double > > &reference, const double x)
bool	approximatelyEqual (const double a, const double b, const double epsilon)
	See knuth book on double comparision.
bool	essentiallyEqual (const double a, const double b, const double epsilon)
	See knuth book.
bool	definitelyGreaterThan (const double a, const double b, const double epsilon)
	See knuth book.
bool	definitelyLessThan (const double a, const double b, const double epsilon)
	See knuth book.
std::string	secondToTime (int seconds)
	Parse the input to the string form of "XX hours XX minutes XX seconds".
double	matlabfmod (const double x, const double y)
	c++ fmod() is not consistent with Matlab fmod() when handling negative number.
double	cot (const double x)
double	acot (const double x)
bool	isEven (unsigned n)
bool	isOdd (unsigned n)

Function Documentation

double acot

(

const double

x

)

bool approximatelyEqual	(	const double	a,
		const double	b,
		const double	epsilon
	)

See knuth book on double comparision.

Parameters

a	first parameter
b	second parameter
epsilon	depends on the context, and determines how equal you want the numbers to be.

std::vector<double> array2vector	(	const double *	in,
		const int	size
	)

std::vector<std::vector<double> > array2vector	(	const double *	a,
		const int	N,
		const int	M
	)

create a 2-D array from a 1-D array specified by N rows and M columns.

double bandwidthToGaussianStdDev	(	unsigned	bandwidth_defn,
		double	bandwidth
	)

void convertIndex	(	const int	index,
		const int	nZ,
		int	j,
		int	k
	)

Convert the integer index to the indices of the two-dimensional vector.

Parameters

&index
&nZ
&j	contain returned value
&k	contain returned value

void convertIndex	(	const int	index,
		const int	nY,
		const int	nZ,
		int	i,
		int	j,
		int	k
	)

Convert the integer index to the indices of the three-dimensional vector.

Parameters

&index
&nY
&nZ
&i	contain returned value
&j	contain returned value
&k	contain returned value

double cot

(

const double

x

)

bool definitelyGreaterThan	(	const double	a,
		const double	b,
		const double	epsilon
	)

See knuth book.

Parameters

a	first parameter
b	second parameter
epsilon	depends on the context, and determines how equal you want the numbers to be.

bool definitelyLessThan	(	const double	a,
		const double	b,
		const double	epsilon
	)

See knuth book.

Parameters

a	first parameter
b	second parameter
epsilon	depends on the context, and determines how equal you want the numbers to be.

void deleteArray

(

double **

data

)

Free the memory space created by vector2array()

void deleteArray

(

double *

data

)

Free the memory space created by vector2array()

bool essentiallyEqual	(	const double	a,
		const double	b,
		const double	epsilon
	)

See knuth book.

Parameters

a	first parameter
b	second parameter
epsilon	depends on the context, and determines how equal you want the numbers to be.

std::vector<int> findEqual	(	const std::vector< double > &	reference,
		const double	x
	)

Find the index of the elements that are equal to x.

std::vector<int> findEqual	(	const std::vector< std::vector< double > > &	reference,
		const double	x
	)

int getNextPower	(	int	N,
		int	base
	)

std::string getRandomFileName

(

std::string &

prefix

)

Generate a h5 file name in format of "prefix_year_month_day_hour_minute_random.h5".

Returns

std::string the file name

bool isEven

(

unsigned

n

)

bool isOdd

(

unsigned

n

)

double matlabfmod	(	const double	x,
		const double	y
	)

c++ fmod() is not consistent with Matlab fmod() when handling negative number.

This function follows the Matlab convention.

std::string num2str

(

const double

x

)

Use the std::ostd::stringstream to perform the conversion.

std::string secondToTime

(

int

seconds

)

Parse the input to the string form of "XX hours XX minutes XX seconds".

Parameters

seconds

std::difftime().

std::vector<double> solveTridiagonalSystem	(	const std::vector< double > &	a,
		const std::vector< double > &	b,
		const std::vector< double > &	c,
		const std::vector< double > &	d
	)

solve Ax = d problem, where A is a tri-diagonal system specified by its lower, main, and upper diagonal.

See [Schwarz1989] for the algorithm to perform LU decomposition on A and use backward/forwad substitution solve the system.

Parameters

a	main diagonal
b	lower diagonal
c	upper diagonal
d	right hand side

Returns

x

double str2num

(

const std::string &

s

)

Use the std::istd::stringstream to perform the conversion.

double* vector2array

(

const std::vector< double > &

a

)

copy the content of the vector to an array, which can be directly written to the h5 file.

This method dynamically creates an array using new and returns the pointer to it. Cannot be used too often to avoid allocating too much memory space.

Parameters

a	vector<double>

double* vector2array	(	const std::vector< double > &	a,
		const unsigned	size
	)

copy the content of the vector to an array, specified by size.

If size is longer than the size of the vector, 0 will be padded at the end.

int* vector2array

(

const std::vector< int > &

a

)

double** vector2array	(	const std::vector< double > &	a,
		const unsigned	M,
		const unsigned	N
	)

copy the content of the vector to a MxN 2-D array.

The array occupies an contiguous space in the memory.

std::vector<std::vector<double> > vector2vector	(	const std::vector< double > &	a,
		const int	N,
		const int	M
	)

void writeToTxtFile	(	const std::string	file_name,
		const std::vector< double > &	data
	)

void writeToTxtFile	(	const std::string	file_name,
		const std::vector< std::vector< double > > &	data
	)